Replace media inside word / powerpoint file as zip container

Question

I received several Powerpoint presentations with (unnecessarily) very large movies embedded, resulting in files even over 1Gb.

I mean to reduce the file size. I tried the File -> Reduce media size (or the like, my Office is in Spanish) way, and it barely changed file size.

Since newer Office files are simply zip containers with a different extension, I mean to reduce the media file sizes themselves. What I tried to replace file media2.mp4:

1. Changed .pptx to .zip,
2. Extracted file media1.mp4,
3. Copied it into media2.mp4,
4. Replaced file media2.mp4 inside the .zip with this alternative file (simply click and drag),
5. Renamed back to .pptx,
6. Checked that the movie was effectively replaced in the animation.

Is it expected that this works generally, even when replacing original media with another file with different parameters (different size, resolution, bitrate, framerate, you-name-it)?