The search/account/upload bar at the top of YouTube that follows you as you scroll down the page can get really annoying on small screens or if you want to get a large player or read many comments at once. This simple script changes few style properties to fix that and make the bar stay on top instead of following you. It also adds a small triangle icon button that you can click to skip past that header (much easier and more consistent than trying to scroll by that tiny amount with your mouse wheel).
This script works with new layout introduced mid year 2017, unlike the old one: https://greasyfork.org/en/scripts/8974-youtube-obnoxious-bar-fix
Much earlier versions automatically clicked the button mentioned above but it was a bit inconsistent (it only does it on first video loaded) so I disabled it. If you don't mind that inconsistency then you can re-enable it: go to the installed script code and find this line:
and uncomment it (remove the
from it, leaving just the