It looks like most songs that previously worked no longer work. I don't know if it's the case for every song but it might be due to copyright claims on YouTube (when there is no loading circle stuck in the middle of the screen this is the case). However, I have noticed a select few videos do load (for me, at least).
Maybe it would be beneficial to the few people to play to list out the working songs. Please help contribute to this thread!

Songs that I tested and worked for me (as of April 18, 2017). Not guaranteed to work for all users due to region blocking (copyright). Should work if you live in Canada.

[Synthpop] Into the Groove - Madonna


[Alternative Rock/Punk] Romantic Rights - Death from Above 1979 MAY NOT WORK FOR ALL REGIONS


[Classical] Danse Macabre - Camile Saint-Saëns


[Disco] Stayin' Alive - Bee Gees


[Pop Punk] Kill The DJ - Green Day


[Dubstep] Do I See Color - Adventure Club


[EDM] REALiTi - Grimes (Original Demo Version/Music Video)


[Electronica] Fall In Love - Phantogram MAY NOT WORK FOR ALL REGIONS


[JPOP] Realize - Nami Tamaki


[JPOP] Believe - Nami Tamaki Warning this video has like zero bass for some reason so it sounds like garbage, I'm sorry


[Synthpop] Mad World - Tears For Fears MAY NOT WORK FOR ALL REGIONS

what i found out after playing for a long time was that only most songs from 2015 and older with 1k views are playable, maybe rarely some 2016 songs because i put a song from 2016 on there and it worked