Video freezing during playback

I Have an iPad 4 with IOS 8.4.0 and am experiencing problems while playing back videos that I have purchased. The video will freeze after a short time and will completely lock everything. I have to perform a reset to unlock everything. I have checked my wi-fi connection and it is more than fast enough to run the video. I have 2 wi-fi connections and I experience the problem on both. I can watch BBC iPlayer without any problems. I have reset wi-fi settings but still experience the problem. if I download the video to the iPad I still have the problem. Any advice would be most appreciated.