hello, other users of the extension seem to have the same issue. please directly contact the extension developers through the means provided at the homepage - they can likely give you more detailed guidance and are the only ones who can fix bugs or make necessary adjustments in the addon for new firefox versions. thank you...

This works for me on YouTube. Cancel the download and then immediately right click and choose retry.

There should be an update to this addon available. Please let me know if the update fixes the issue.