i cannot play a video all the way through it loads and shows up but then stops after about 4 seconds
Sally, welcome to the AndroidForums. Glad you signed-up

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I've had this happen to me, too...
Not sure if you mean downloading or playing something that's already loaded on your device. If its a downloading thing, then it could be the internet connection quality / download speeds, slowness of source site, slow app and/or phone, etc. (or combination of all these).
If its something on your device already, it could be the app that doing the playing, or a shortage of memory on your device (might try playing the video after a fresh reboot to see if that makes a difference), or the speed / processing power of your device itself.
Dunno...
Anyway, glad you signed-up... If you let us know what type of device you have, we can point you to a specific forum where others who have your same device might have also experienced this and can point you towards a solution.
Cheers!