Video Streaming : how to use VLC instead of GStreamer

As EMLID doc is not very comprehensive on how to stream video, here are some questions for which I did not find any satisfactory answers yet.
I would think it could deserve a whole separate chapter to get this well described.

- How to record the live stream from GStreamer?
On the Rpi : I understood this can be done through the “tee” function, but this require to record all the flight at once (recording at startup). I would appreciate to trigger the recording during flight : I understood this can be done by using VLC on the client… but I don’t succeed to create a .sdp file that gets the stream properly! I only get the first frame of the stream and the video freezes. I can get a new frame every time I click on start/stop or next or preview buttons.
Could someone give a compatible executable command for Rpi and for PC .sdp file would be great.
Here is the .sdp file I am using
m=video 9000 RTP/AVP 96
c=IN IP4
a=rtpmap:96 H264/90000

- What is the best compromise in terms of resolution and FPS settings?
I am running a RPi3/Navio2 set-up. When using the standard setting from the EMLID docs, my quad is extremely lagging, not responsive at all. I only come back to normal flight behavior when I stop streaming video. I will try lower resolutions and lower frame rates but this seems to me a bit strange that processor power is not priorily used for flight controls. I would have expected my video to be lagging and not the flight commands…
This is a clear showstopper for live streaming in flight currently

Thanks guys for your inputs!