Fix main thread checker warning

[sryze]

This fixes a warning related to the use of -[UISwitch isOn] on non-main thread:

=================================================================
Main Thread Checker: UI API called on a background thread: -[UISwitch isOn]
PID: 9512, TID: 659771, Thread name: (none), Queue name: com.apple.avfoundation.videodataoutput.bufferqueue, QoS: 0

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[sryze]

I signed it!

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CLAs look good, thanks!