Example: If the video inbound has a resolution of 1920x1080, a &scale=50 would limit it to 960x540 instead.
The nice thing about this is that it doesn't matter which resolution their camera supports; the scale is software based and doesn't care about resolutions or aspect ratios.
This can help a viewer reduce frame stuttering, cpu load, and improve frame rates, without having to have the guest rejoin the stream.
Requires the publisher of the stream to support dynamic scaling; Firefox and Chrome should be supported.