iTunes will only allow the playback settings (located under the options tab) to be changed one file at a times. For all my videos, I like to flag my playback options to "remember playback position" & "skip when shuffling". iTunes offers no way to make these changes to multiple items all at once. Is there a way to apply these changes using MP3tag?
See the help for supported fields:
Do you know whether these settings are actually stored in the tag or are just something that iTunes holds in its own database?
You could find out the latter by examining a file where you set the option with a hex editor.
I do not know where they are stored but they are kept. Once you select these 2, save changes & open back up - that video will forever keep those settings unless they are changed (if that helps any). I'll look into that last option. Traveling today but I will as soon as I can, I will.
It would be interesting to see how the settings are for the same file on a different machine or how they are when you delete that file from the iTunes library and then re-read it. If the settings are still the modified ones, then iTunes will probably save the setting in a file. Otherwise it is most likely an iTunes database thing. And MP3tag will not modify the iTunes database.
I'm gonna give up on this for now - but wanted to thank you for trying to help. 
What about select the files in iTunes, right click select "Get info" and then switch to options and see if you can change the settings for the files selected
Ignore the warning about "Are you sure you want to edit information ...."
The time info is stored in the iTunes db file, not in a tag.
He is asking for " I like to flag my playback options to "remember playback position" & "skip when shuffling"." No mention of time info and those options can be edited with Multiple File Select in iTunes
They can be editted only in iTunes, but these are not stored in any tag that can be externally editted. These are only part of the iTunes database.