Try pasting these this link on try.discourse.org:
The link’s title is Timecop1983 - Let's Talk (feat. Josh Dally) _ Remaster but the generated title in Discourse will be Timecop1983 - Let:
Colar um link no campo de título do compositor corta o título se houver um caractere de citação nele
9 curtidas
It looks like the issue is at youtube_onebox.rb#45
The single-quote (') in the title isn’t html-escaped so it closes the attribute value early, which gets sanitized away
Edit: submitted a pull request
8 curtidas
Merged, thank you for your contribution 
6 curtidas