30fps for 60fps streams
Playing streams at 60fps leads to lots of short buffers and regular intrerruptions. Having an option to play 60fps streams at 30fps regardless of whether the streamer only offers the source, should be a feature.
Not mentioning that 60fps is very heavy on CPU. Reducing it to 30fps solves the problem and CPU is used at minimal level. So even without quality options every viewer should have an option to reduce fps that their PCs wouldn't explode while watching a stream.