Enable Video models for other tasks

[bhack]

🚀 The feature

It would be nice to enable video models to be used as encoders for other tasks then classification.

Motivation, pitch

It seems that video models (e.g. mvit, swin video..) are strictly connected internally to their classification head.
It could be useful to let use them in others tasks. Just to make an example we could use them as a multi-scale encoder to be connected to other components like an encoder-decoder architecture for video segmentation, 3d medical segmentation etc..

Alternatives

No response

Additional context

No response