I have usually found Video DownloadHelper eminently reliable, but since installing Firefox 57.0.1 it has become dysfunctional on most of the sites I use: when I attempt a download most often it will only download a relatively tiny file in M3U8 format.

I was slow to realize the problem, as I found the update needed for Video DownloadHelper enough of a surprise that I hesitated about installing it. See this post:

https://www.linuxquestions.org/quest...ox-4175618198/

When after finally installing the update I ran into difficulties I hoped that this was a small bug that would soon be rectified, but it seems to be taking a while.

I considered following the suggestions in the post above, but had difficulties installing the "Open With" add-on (it seems to be having its own difficulties with Firefox 57.

I removed and reinstalled the add-on, without result. I also tried installing Video DownloadHelper on Chromium, but it did not work there either.

Are other people dealing with the same problem? Is installing an older version of Firefox an option? Or perhaps Sea Monkey?

I am currently running Linux Mint Cinnamon.

Running an older version of Firefox that was installed on an older computer worked. This was not an option I would like over the long term.
But at this point Video DownloadHelper upgraded from 7.0 to 7.1, so my problems seem to be over, until the next time!