Hi. Is there a way to batch rename the contents of the comment field. For example I have 300 files
and they all have something different in the comments field. I want to perform an action that will
replace all 300 (batch)with a new single comment. Any help is greatly appreciated. Thank you.

Load those 300 files into Mp3tag.
Select them all.
In the tag panel (an the left): enter the new comment
Press Ctrl-S to save the changes.