Sequencer does not work with Videos

Hi, so I am very perplexed on how anyone is able to get sequencer to work and render anything to timecode or to dialog with no lag and perfectly in sync. I have an mp4 video playing in my scene and a few characters and a bunch of fountains. I have checked a million variations of checkboxes exporting and trying rendering and still lag or weird playback issues. If I turn my fountains off (NIagra) it seems to be fine but I have to restart Unreal to get it to be in sync. if I look at my processor and my graphics car and ram it’s all fine and barely working. There are like 5 or 6 places to make sure you are running at 30 frames per second and I have checked all of that. Rendering is not possible I have to go to game view and Immersive view and then do a screen capture to get things in sync.

Ideally I would export the video and my water and fountains and video and characters would all be in sync. How do other people do this? it seems impossible?

I could not count the hours wasted on this problem.

windows 10
quadro rtx 5000
unreal version 4.23.1

Any ideas would be greatly appreciated.

you using media textures in sequecner?