I have lowered the level of "ZSTD" to get equal time with "FastBackup" and have the same result of compression, if no less in favor of "ZSTD".;)
Logically if I used the level "ZSTD -21" was obtained a longer processing time of about ten seconds, but a greater compression threshold of 2%.
I have also noticed that by testing individual files "FastBackup" with level from -m4 to -m9 compresses better than "ZSTD" with level from -5 to -21, and viceversa.:)
The two compressor will equate, and "FastBackup" also remains a valid compressor.
P.S I sent you a PM.

hey felice this is a litle help for your nice idea about videos.

Nice @ChronoCross check this JPG lossless and lossy compression.
Compress each file from folder into 7z.
Recompress zip files with brute deflate compression.

Welcome back Tio Gozarck.... :)

Well..What if we use packJPG on those JPG output instead of JPG optimize so we can get about 20% ratio

Hello Ramirocruzo my good friend. Do you have packjpg in CLI? I have a gui mode only. I like the idea of chronocross extracting images from videos and then compress those files and encode into a bik/bik2. Bpg encoder is amazing the quality is even better than FLIF.

Enclosed CLI with all the usage information Tio Gozarck. :D