Aaaah, I finally understand your topic. I was misled by the typo in aniamtion to simply ignore that aspect. Please spell check before posting, especially the title. Otherwise, it becomes much harder to find your question and answer later on.
I now discovered the article on Revit - compressing walkthrough videos and assume that is what you are after:
https://knowledge.autodesk.com/support/revit/learn-explore/caas/sfdcarticles/sfdcarticles/Revit-comp...
Please note the remarks there:
> Once you have exported your walkthrough from Revit, the resulting uncompressed video file will most probably pretty big for its quality - you will need a 3rd-party codec to compress it for further optimizing the balance of quality and filesize. There are multiple products available on the market. Explore available solutions by gathering information from those 3rd-party vendors or simply from the internet.
FFmpeg is certainly a good choice for that.
Basically, ffmpeg is an external program. You could run it externally on the command line. Are you trying to go one step further and integrate a call to launch ffmpeg into your Revit add-in? If so, you might find the ffmpeg library and a .NET wrapper for it useful: