I just tried both 6.2-3482 and 6.5 and they both operate the same for me, neither version autostart.
When a quad has been published and you assign a Video File to it via the sequencer, that video will try to use the same properties as the quad from layout; so if you want it to autostart, you need to assign a video to it in layout mode and set that video to autostart. Then when you replace it from sequencer, any video assigned to that quad from sequencer will autostart as well.
If you can test 6.2 again and you do see different behavior, please attach a sample project and I can investigate the issue further. Note that all 6.5 builds are still beta builds and have not had any formal testing. 6.2-3526 is the latest officially tested software.
#XPression