Suggest you turn off AdBlocker for YouTube™ Video 0.1.5, this Adblock Plus Test, turn back, go into it and make adjustments or rules.

Or : Please : https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer and https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles then https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings TEST....... If no issues then Extensions which need to be added back in 1 at a time and tested ..... Or it is your Profile : Make a new one and test ...: https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

Please let us know if this solved your issue or if need further assistance.

This worked only one has to keep on redoing in order to have it work - IT IS NOT A SOLUTION! NEEDS TO BE FIXED!

However, I changed the default engine from Yahoo to Google and again I can't see the comment window. I did the steps again and then it worked again. But, right after I enabled anything that I previously had - I lost the Youtube comments window again. I am sure that this is somehow a bug in Firefox and it would be nice to be fixed. Basically it is enough to just close Firefox and open again to have to go through steps again to make it work for that session etc...

I downgraded to version 56 - version 57 is not ready yet!