A regular expression to match a YouTube Channel ID.
/https?:\/\/(www\.)?youtube.com\/channel\/UC([-_a-z0-9]{22})/i
Matches:
- https://www.youtube.com/channel/UCv4Cecqpm3cOv7N5N9NkMsQ
- https://www.youtube.com/channel/UCS94J1s6-qc8v7btCdS2pNg
- https://www.youtube.com/channel/UCvlE5gTbOvjiolFlEm-c_Ow
Non-matches:
- http://www.youtube.com/watch?v=BeG_UU-Bf5k
- http://youtu.be/BeG_UU-Bf5k