Well after much experimenting and advice seeking from people who know more than me (on here)
I have come to the conclusion the one thing you need and need to understand is....
I have continued in my quest to use mix my photos (mainly birds) in with video I shoot..
I have tried to make a short film of autumn colour and reflections.
This video was rendered in corel video studio, which worked last time perfect if I saved as avchd. This time (same camera same everything) it only played smoothly when saved as MP4.. In fairness I think youtube is half the trouble...but this time when I saved as avchd , even though it played on my pc, when I uploaded to youtube my voice went out of sync.. Only when I uploaded as mp4 and 720p did it come out right....
So this video http://wildaboutfilms.com took
8 different render settings
6 different uploads to youtube
to get right. And even then I had to compromise by not uploading 1080p
and the best of it is, I know what worked may or may not be right next time. In fact the settings I used that worked this time, did not work last time.