I was reluctant to link to youtube, but I couldn't find it at the usual places. Youtube often cuts out stuff from movies on their site.
I'll continue looking and if I find it somewhere else, I'll post.
Here are two more...
https://tv.apple.com/us/movie/forbidden-planet/umc.cmc.6g2tzfazttkt1qz0cqmxjnd9l
https://archive.org/details/forbidden_202102
There's a copy at dailymotion, but I think that's pirated copy.
@Pat Mmm, archive.org never stops loading and tv.apple.com wants me to pay. Also not really seeing indication of subtitles alas.
@Pat I just kinda wanted to see what Leslie Nielsen looks like in here.
I think the archive files are just for download (and play offline). I didn't look at them so I don't know if they were created with subtitles.
Did you try searching youtube from there. Maybe they have it somewhere else in the NL site.
(The one here on the US site is not free, but maybe they have one that that's free with ads.)
It's an old movie so it may not have been subtitled, but youtube has their auto-subtitling which is passable.
@Pat Aww, video unavailable here.