"a song has to be transmitted and re-distributed orally,"
A SONG CAN BE TRANSMITTED ORALLY - IN PRINT - VIA ELCTRONIC RECORDING - THROUGH FILM..... IN ANY WAY YOU CAN THINK OF THAT ONE PIECE OF INFORMATION PASSES FROM ONE PERSON TO ANOTHER - AND STILL BECOME A FOLK SONG.
At one time, and in certain communities, people were making songs, passing them on by whatever means they had to hand, and other people were taking them up, singing them and taking ownership of them, so that a song that may have originated in, say Norfolk, could end up in Somerset, or Lancashire or Cumbria, or any part of Ireland or Scotland, and become a Somerset or Lancastrian..... or wherever it happened to land song - the new recipients would regard it as theirs, as speaking for them, as being part of their history - it would become part of their voice just as much as it was the voice of the original creator.
That is part of how folk songs were created and that is what is no longer happening.
A song made today remains the property of the creator - it continues to bear his/her name, quite often it carries an instruction that if you want to make it generally known, you have to pay for the privilege of doing so.
Nowadays, even if you sing a newly made song in a club, or even a song created a couple of centuries ago, the club has to pay a P.R.S or I.M.R.O. levy.
Folk songs were public property - no individual claimed ownership of them, in most cases nobody even knew who created them - they were virtually all anonymous.
It is still possible for folk songs to be created where the circumstances are still in existence.
The Irish Travellers we recorded in London were still making songs concerning their lives and experiences as late as the late 1980s - they possibly still are, though the urbanisation and the loss of the old trades make that less and less likely as the communities dissipate into houses "The old ways are changing".
We recorded several - in none of the cases we could not find who made them.
Children were making songs until recently - I don't hear of or see many of them skipping or bouncing balls, those activities which led to the creation of songs - there may be a song tradition arising from mobile phones, but I've yet to hear of it.
Football chants have some claim to being 'folk' - I personally don't find them particularly interesting or artistically creative, they don't say much other than "We are the greatest".
There was a great new song-making tradition in the 50s and 60s with The Aldermaston Marches and the Holy Loch Protests - songs being created on the spot and passed down the marches - doesn't happen now.
Some new songs have taken teetering steps towards becoming folk - we've recorded Freeborn Man and Shoals of Herring from Travellers on several occasions - their becoming folk songs depends entirely on the Travellers and any other community who might take them up retaining a living tradition capable of transmitting songs so they become everybody's property other than just the composers'.
I'm delighted that people are still making songs using the old forms - I've just been looking at Eric Winter's 'Flowers of Manchester and remembering the first time I heard it sung at Terry Whelan and Harry Boardman's club in Manchester all those years ago - it moved the audience to tears, including me (and I detest football) .
It should have become a folk song but it didn't - ir remains Eric Winter's great song - I haven't even heard it sung for forty years.
Another song, by Pete Smith, a shop steward from Manchester who wrote about his experiences working in the factory which manufactured dyestuffs for the textile industry - had all the elements to become a folksong - most people have never heard of it - can find no trace of it.   
The process that once created folk songs no loner exists, the opportunity for us to claim songs that other people wrote as our own no longer exists, if we want to issue them electronically, we have to pay for the privilege, even if we sing them at clubs, there is now a good chance that we will have to pay for the privilege of doing so, the bulk of which will disappear into the bank accounts of The Rolling Stones, The Beatles or the Michael Jackson estates.   
The revival democratised and freed up a wonderful corpus of song and music for us all to perform and listen to and claim as our own - that has now been replaced by a dwindling number of venues which might or might not present folk songs, but the tendency seems to be as far away from that music as you can possibly imagine.
MAKE UP YOUR OWN MIND
I'm not entirely satisfied with the existing definition, but at least I have something to point to and say - "that's what I mean".
I have hundreds and books and albums I can direct people to who might be interested and say, "that's where to look if you want to read or listen to folk songs".
If somebody wants a fairly comprehensive list of them, I'd direct them to the Roud index - most of them are covered there.
Hopefully, before the end of the year our County library will put up on their website, 400 plus songs we have recorded over the last 40 years in this area, many of them containing the social and political (and sometimes personal) history of the people who lived here
Over the last year I have been taking in masses of information about the place I now live in and the people who once lived here, just by annotating the songs.   
The people we met were incredibly generous in giving us their songs, many of them became life-long friends - we now have been given the opportunity of returning those songs to where they really belong - a great privilege.
If the songs are taken up and sung, if song manages to become as popular here as traditional music has become, it will mean that the songs will survive for the forseeable future, as entertainment and as as an essential part of the unwritten history of West Clare.
I'm a bit chuffed about that
Jim Carroll

THE CLAYTON ANILINE SONG
Pete Smith, Mancester mid 1960s

1 Been working at dyework for nearly five years ,
Been charging the naptha's that give yer the **pap,
They send it from *ICKY for us to shove in
This **vitrol and chloric as makes us all thin.

2 Well I rise up for Clayton at five in the morn,
And for smoke and for fumes, yer can't see the dawn,
I'm releivin' old Albert, he's been here all night,
The poor old bugger looks barely alive.

3   His chest is sunk in and his belly's popped out out,
And believe me, my friends,! t's not bacco or stout –
It's the **napthas and paras have rotted his bowels,
While making bright colours for Whitsuntide clothes.

4 I gave him my ****milk ration and packed him off home,
I' ve five tons of this naphtha to charge on me own,
I'm wet through with steam and the sweat of me back
And through wieldin' this shovel, I'm beginning to crack.

5 Well I'm damned if I'll work in this hole any more,
For my belly feels tight and my chest is right sore-
I think of old Albert his face white and drawn,
He'll be back here tonight and just prayin' for dawn.

*    I.CI.- Imperial Chemical Industries nicknamed "ICKEY'
**   Chemicas for dye-making
**   Paploma of the bowel – cancer caused by fumes from dyestuff    manufacture
**** A pint of milk was given to each worker each day to 'ward off' cancer.