Wow Kath, that is
so cool! I never really noticed that strip of cloth in the original pilot before, just that Mick looked nervous and was moving things around a bit. What an eye you have for detail!! Hmm... wonder if he had been using it as a tourniquet, to raise a vein to inject himself with blood. That might be why he didn't want to have it out while Beth was there.
And in this pic it looks like that is Beth on the monitor.
I wonder if they originally did a scenario where where Beth showed up while he had his shirt off and had been injecting himself with blood, and later changed that to having Beth's mom show up at such a moment in the flashback.

In the original pilot as we saw it, when Mick was looking in the monitor at Beth, he had his shirt on.