Was working absolutely fine until the update, now experiencing all sorts of problems. Like the old saying goes " if it isn't broken, fix it until it is!" Had to disable it.
Edit: Reinstalled Version 2.0.101 from here, https://addons.mozilla.org/en-GB/firefox/addon/enhancer-for-youtube/versions/ and everything appears to work as before, turned off auto updates for the time being. Will update when fixed.