AVCodec is installed after the reboot in some cases as the needed permissions are not setup of older images. It does take a bit longer the some of the other updates.
By interrupting the update you have put it into an unknown state, it may be that one part of the system believes the update is successful, while the other still can't find the needed components, and so tries to install them.
I'm going to have to think about how to fix this :-/ .....
Probably the fix is to purge avcodec and then reinstall, but I don't want to force that for everybody.
Typing that I've had an idea, will get back to you....
The crash when starting PlayVideo without avcodec installed was just fixed, (I though I had fixed it before but missed an underscore....)
