mjpeg stream > 1s delay

#### Issue details
I have a raspberry with [RPi Cam Web Interface](https://github.com/silvanmelchior/RPi_Cam_Web_Interface) installed to get a mjpeg stream of my camera. This works great in the browser and has a no noticable delay. But when I use the mjpeg stream on Mission Planner, I get about a 2 second extra delay compaired side to side with the video in the browser. Are there any buffer or timing options to configure this? Thank you for your time.

#### Version
1.3.49.1

Reproduce the reported side-by-side delay using Mission Planner 1.3.49.1, the RPi Cam Web Interface MJPEG stream, and the browser comparison. Start by checking whether Mission Planner exposes buffer or timing settings for MJPEG video, then determine what behavior would confirm that the extra delay is resolved.

Written by the indexing model from the issue text.