Default Blue screen flicker while watching youtube

Hello everyone, i have a weird problem, everytime when im watching youtube (app) on my SP device, i get every now and then an annoying blue screen flicker which last for like 5 seconds. The weird thing is, that this problem not happens on every Video i watch, like i said above, every now and then, its like random.

Also, what i realized yesterday, after sometime my Phone freeze for like 3 seconds while watching youtube, also the sound gets weird. I dont know what causes the problems, is it, because im still using the stock youtube app version which comes with the phone, do i have to update the app in order to eleminate those problems?

What i already did: factory reset
What im using: Android 4.3 latest, not rooted and BL locked