Moves the controls under the video and makes the UI look like it was before august 2015
The bright background is normal, but the dialog was pushed off-screen for some reason. I've narrowed the problem down to a certain css rule that was supposed to move the content under the video 35px down (to make room for the controls). Moving it down with a transform seems to conflict with how the dialog shows up...
Luckily I've found an alternative way to move the content down a while ago (but didn't include it, because it didn't seem necessary), which fixed it (v1.12.0).
Reporting dialog glitch
When clicking to report a comment, a bright background would just appear across the whole page making it impossible to get out of.
I don't know about other dialogs causing this, as this is the only one I have found so far...