As we've discussed before, in general, if you just ASK people nicely, they'll often point you to what you seek. We've seen this before in getting copies of papers and articles that are behind paywalls, and in getting preprints of stories that never quite appeared in print.
Following that precept, I managed to locate the creator of "The Vanishing Cape Breton Fiddler," Ron MacInnis, and wrote to him asking for advice about where to find the video.
He wrote back almost instantly and pointed me to an open-access copy of the film!
There's no way to pay for streaming or access, but as Ron pointed out to me, "..a most appropriate and effective way to show support would be to make a donation to the Celtic Colours festival, who have done great work in preserving the culture."