HTC Desire C - Why won't it play movies from google play?

[wadadlis]

I have an HTC Desire C.

Why won't it play movies that I have downloaded from google play?

DS doesn't understand why mummy's phone is so crap.

I don't have a good answer - do you?

Sorry, don't have the HTC desire or watch movies from google play, but didn't want to leave you unanswered!

Thank you! Actually it's my DH's question but he doesn't understand mumsnet so I had to send this for him!