[XODIDOX]

Seems there is a misunderstanding for this label. The IsVideoExtras infoLabel is for the extras item itself, not for the parent movie item which will always be false. When in library, it's only applicable when you turned on the "Show video with multiple versions as folder" option, this container contains all movie versions and extras, you can use ListItem.IsVideoExtras to check if a specific one is extras or version. In the video version dialog, you should check the Container(51).ListItem, instead of ListItem which is the parent movie item.

I see, I did not think to check that. It is indeed true when the folder option is turned on.

As a general rule, checking mediatype is "videoversion" (a new media type) before checking IsVideoExtras.