Hi,
The Video delay should save (optionally maybe?) newly recorder frames - explanation:
1) Video delay is created at 30s long buffer
2) buffer is fully filled
3) delay saved to avi (30seconds)
(delay doesn't record while saving)
4) delay finishes saving
5) delay starts recording again
6) 17 seconds elapsed and there is no much time for changing length to save,
newly saved delay has 13s of old frames at the beginning and 17s of new frames.
I think, that Video delay should save only new frames, do you?

is any chance to improve the Video delay?