Can't change details on Twitter videos

1 Download an .mp4 video from Twitter
2 In Windows Explorer (windows 8.1), right-click on the filename of the file I just downloaded and examine the Properties | Details tag.
3.None of the fields are modifiable.
4 Open that directory in Mp3Tag, select that file, and enter a Comment.
5 It shows in the Comment field in Mp3Tag.
6. Save and close mp3.Tag,
7. Examine the Details in Windows Explorer, the comment isn't there.
8. Open mp3tag, the Comment is still there.

In all other instances, the data in the Comment field of mp3Tag is the same as the data in the Comment Field in Windows Explorer. Is this a known issue? Is there a workaround?

thank you

I would first of all check whether the downloaded file is OK.
See also this thread:

I don't know, though, if that also applies to MP4 files.

The video plays fine.

I've never had this problem with mp3 files.

Unfortunately, this does not tell whether the rest of the file is OK.
See e.g. here:

So why does mp3Tag show the comment, but Windows does not?
Are they looking at the same data?

You could ask the same question on a Microsoft site.

If you do not feel like examining your file, it may be easier, if you supplied it with a link to a file hoster or something.