This morning I played from the BT Player - Library - Editors Clips
Funny Sporting Moments 2 -- opting to select play all HD
3 of the clips played ok but the 4th (Streaker hits Ribery in the face) froze midway through.
the box was not responsive thereafter other than the Youview button which responded once but would not do anything more.
Eventually I restarted the box (holding power button for 8 seconds) - Subsequently I went back into the player and reselected Funny Sporting Moments 2 and it reumed from the point it had frpzenlast time.
I then selected Funny Sporting Moments - opting to select play all HD - this froze on the clip of the manager sitting on the cooler box and again only a box restart would give me a functioninmg box.
So looks like there are issues with the BT Player library and the handshaking between the Bt Player and Youview as BT Player faults should not impact the other functionality of the box.