Frames for Music Videos in List/LowList views

[jingai]

Note that we have to deal with two different aspect ratios here: might be an album cover or a screenshot from the video (which can be 4:3 or 16:9 among other ratios).

Don't add frames if we're currently in an addon, because we can't tell what the icon is!

[jingai]

This is not currently doable (as of Kodi 17) because we can't tell whether ListItem.Icon contains a square icon or fanart (usually a screenshot from the video). ListItem.Art(fanart) isn't implemented in Music Videos so they do it differently.