As a part of the UBB.threads v7.6.0 mobile update (See the Progress Report from 2016.12.04) the regex coding on all of the default tags were cleaned up and enhanced; in the YouTube tag for example we can now match URLs vs URLs in previous editions of the tag; the caveat however is that the tag no longer allows one to just quote the id, it must be a full URL.

Surmising; this:
Code
[video:youtube]s6-DBHXJ_ho[/video]
Should now be
Code
[video:youtube]https://www.youtube.com/watch?v=s6-DBHXJ_ho[/video]

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