They are indeed available on VHS and DVD, we have one of each and they are brilliant.

I've only found them in selected stores ('Borders' to be exact, they have a much larger selection of 'suitable for children' DVD/video) so a search on eBay is your best bet.

ISBN Numbers - 'Soul Music' 5028974104727 VHS Pub 1997
               'Wyrd Sisters' 0440078022724 DVD Pub 2000

Both were originally made in 1996. Hope this helps.

LTS