Does not work correctly with nested brackets.
For example, if you want to eradicate youtube playlists, you'd better locate &list parameter and rebuild the URL without it.
Rather than identifying all parameters for careful string composition.
E.g.
(https?://)?(www\.)?youtube\.com/(watch\?)?((&?v=[^&]*)|(([&#]t=([\d]*h)?)([\d]*m)?([\d]*s?))|(&?index=[\d]*)|(&?list=[^&]*))*
has nested parentheses which are not parsed correctly by this extension.
I'd propose to use
(https?://)(www\.)youtube.com/watch\?(.*)(&?list=[^&]*)(.*)
with this replacement
$1$2youtube.com/watch?$3$5
This way parameter &index= will remain, but won't have any effect.
And the result will be removal of &list parameter which I am talking about.