The issue is not that the data needs to be around for ‘long enough’; the issue is that the API doesn’t expose any means of strictly bounding how long ‘long enough’ is that data needs to be available for.
I maintain this is basically no better than just sleeping for a random length of time before swapping pointers.
It’s slightly vexing that the blog example (from the panda blog no less) of ‘how to make a webcam /movie texture’ uses this exact method; but then that’s not the right why of doing it after all apparently.