Attribute version increment on media and metadata objects

Hi community,

we need to access the previous version of a video (and/or its custom metadata).
When attributes of the video are changed there is no version increment.
On service: media action:get you have the possibility to query a certain version of a media entry.
But its useless if there is no version increment at all.
Question: When does version get incremented?

When you change custom metadata fields on the other side ther is a version increment in the metadata object, but the service: metadata action:get has no parameter to filter for a certain version.
So this is equally useless.
Question: Is there another possibility to filter for a version of a metadata object?

How can I achieve any kind of version comparison for integration purposes?

Any help welcome :-)

greetings
Chris