[Nick Dietrich]

Just in case this helps –

https://www.videocopilot.net/blog/2008/06/fix-quicktime-gamma-shift/

“SOLUTION: After rendering into a QuickTime/h.264 file, open it up in QuickTime and select “Show Movie Properties.” Highlight the video track then click on the “Visual Settings” tab. Towards the bottom left you should see “Transparency” with a drop-down box next to it. Select “Blend” from the menu then move the “Transparency Level” slider to 100%. Choose “Straight Alpha” from the same drop-down and close the properties window and finally “Save.” ”

Just make sure you highlight the video track under show movie properties in order to see the “visual settings” tab. It should work.