>>/29289/
1. I took some liberty in changing your date formats into these:
>  20230510_My Video.webm > [2023-05-10] My Video.webm

Here's a shit bash scribble which does this recursively on a directory tree, using sed.
Replace (find .) with name of a folder to operate on if you're afraid of touching anything else, e.g. (find ./mirrr):

IFS=$'\n'; set -f
for file in $(find .); do
mv "$file" "$(echo "$file" | \
sed -e "0,/\([0-9]\{4\}\)\([0-9]\{2\}\)\([0-9]\{2\}\)\(_\)/s//\[\1-\2-\3\]\ /" \
find:
[code]
for file in *; do
mv "$file" "$(echo "$file" | \
sed -e "0,/\([0-9]\{4\}\)\([0-9]\{2\}\)\([0-9]\{2\}\)\(_\)/s//\[\1-\2-\3\]\ /" \
  [2023-05-10] My Video.webm > 20230510_My Video.webm
replace regular expression in sed with this:
[code]
"0,/\[\([0-9]\{4\}\)\-\([0-9]\{2\}\)\-\([0-9]\{2\}\)\]\ /s//\1\2\3\_/"


2. mitomo7-dropofcandy videos were same as what was already there, you could have just posted a text file with timestamped filenames then. Mega unfortunately doesn't let one operate on archives without downloading full content first, so I had to download both to see what's inside and rename them, and as far as I know, none of client tools allow remote file renaming, especially by pattern, so I would have had to do it anyways xD

By the way, do you happen to know what do these digits after fps mean?
>  holding on 480p30fps 247.mkv

>  dealing with the unexpected 480p30fps 232.mkv


3. In the end here's what's we've got:
Download here:
https://mega.nz/folder/tqdxjSjR#UxAHBVn-_Z2oEgz8f1sxmQ
Streams with Alice are here:
https://mega.nz/folder/cyZHzJKI#YYqjZD6A1jNziJWPO_vbvg
Upload your stuff here (11~ Gigs free, I kept the archives on server):
https://mega.nz/filerequest/bZx4bEUne-A