Excellent! Just Googled my issue of not being able to play Vids on my Gs4, followed the clear data steps, restarted and now my phone works great! Thanks, you saved me a lot of frustration. Should have Googled sooner.
Glad I found this place!
Cheers,
To fix this problem you need to:
1. Go to phone dialer and dial *#0011#. This will bring up Service Mode.
2. Click the menu button and select wifi. This will bring up wifi information.
3. Then turn off Wifi power save mode.
Then go to YouTube or Facebook and try to play a movie. It should work. But you might have to do this process every time you restart your phone.