Add support for YouTube hashtags

[ChunkyProgrammer]

The base url for a youtube hashtag is:

https://www.youtube.com/hashtag/

Example hashtag "minecraft"
https://www.youtube.com/hashtag/minecraft

[gregjacobs]

Hey, thanks for the info, and this would be a good addition. Unfortunately I don't know when I can get to this at this moment, but PRs definitely welcome!

[gregjacobs]

Added in v4.1.0. Thanks for reporting!