>>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):
[code]
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//\[\1-\2-\3\]\ /" \
<<< "$file")";
done
unset IFS; set +f
[/code]

Or similar operation but only on files in current directory without find:
[code]