It's 2022 and Firefox still doesn't allow deactivating video caching to disk.

When playing videos from some sites like the Internet Archive, it writes several hundreds of megabytes to the disk, which causes wear on flash storage in the long term. This is the same reason cited for the use of jsonlz4 instead of plain JSON. The caching of videos to disk even happens when deactivating the normal browsing cache (about:config property "browser.cache.disk.enable").

I get the benefit of media caching, but I'd prefer Firefox not to write gigabytes to my SSD each time I watch a somewhat long video. There is actually the about:config property "browser.privatebrowsing.forceMediaMemoryCache", but as the name implies, it is only for private browsing. The RAM is much more suitable for this purpose, and modern computers have, unlike computers from a decade ago, RAM in abundance, which is intended precisely for such a purpose.

The caching of video (and audio) to disk is completely unnecessary as of 2022. It was useful over a decade ago, back when an average computer had 4 GB of RAM and a spinning hard disk (HDD). Now, computers commonly have 16 GB RAM and a solid-state drive (SSD), which makes media caching on disk obsolete, and even detrimental due to weardown. HDDs do not wear down much from writing, since it just alters magnetic fields. HDDs just wear down from the spinning and random access, whereas SSDs do wear down from writing. Since media caching mostly invovles sequential access, HDDs don't mind being used for that. But it is detrimental to the life span of flash memory, and especially hurts live USB drives (USB drives with an operating system) due to their smaller size.

If I watch a one-hour HD video, I do not wish 5 GB to be written to my SSD for nothing. The nonstandard LZ4 format "mozLZ4" for storing sessions was also introduced with the argument of reducing disk writes to flash memory, but video caching causes multiple times as much writing as that.

The property "media.cache_size" in about:config does not help much. Setting it to zero or a low value causes stuttering playback. Setting it to any higher value does not reduce writes to disk, since it apparently just rotates caching within that space, and a lower value means that it just rotates writing more often in a smaller space. Setting a lower value should not cause more wear due to wear levelling, but also does not reduce wear compared to a higher value, since still roughly the same amount of data is written to disk.

Media caching also applies to audio, but that is far less in size than video. Still, deactivating it without having to use private browsing should not be denied to the user.

The fact that this can not be deactivated is a shame for Firefox.