WEBM vs Original
The WEBM version does use compressed images... but the original version also had 'compressed' images almost nothing was a PNG in the original.
GIF animations inherently decrease the quality of the source by limiting the color palette down to 256 colors, which has to be overcome by dithering techniques... and a lot of the original gif files used a dithering technique which introduces a lot of artifacts.
I think because F95 compressed versions are super compressed to the point where size is more important than quality, people have a misconception of what the WEBM version is... any additional compression ran on images was chosen at a point where it should be hard to notice a significant difference. I won't say that it is a 'lossless' version of the original, but unless your going side-by-side with the originals and specifically analyzing them... it shouldn't matter over the course of normal gameplay.
Included HTML vs Standard HTML vs Modded HTML
Recent mods based off the last released standard version should also have support for the WEBM integrated, I worked with
Beornwahl to specifically give him the ability to use WEBM/MP4 files instead of GIFs so that the size of the game did not continue to spiral up and up and up.
The main difference between the HTML included with the download are some minor bugfixes that aren't integrated in the released version and the CSS style sheet was changed to have a different color scheme and a larger allowed space for the 'story' part of the interface.
I do think both of the mods have corrected most of the same bugs... I think the only thing that might have been specifically changed by me was to do with adding the options to control the 'Elven' music theme.