Yeah, if I were you, I definitely would not use a dildo during the heaviest days of a period. When I used to use dildos (during a period), I made sure to have a dark towel underneath me and did the "riding the dildo" position. DO NOT do the position of laying on your back, because that's the worst position you could do while on a period. With the riding position, you can position yourself on cam so that the guy sees a full body shot of you without noticing anything when blood starts trickling out.
BUT I will say...when you start to feel blood trickling out, either A) move your cam's view so that it's just on your face down to your stomach. So the guy just sees you naked with your boobs bouncing around like crazy...guys love that shit.
Or B) (I don't really like this option) you can put your hand down there and act like you're playing with your clit while riding. But really, you're just covering up yourself so the guy doesn't get a view of the blood trickling out. That's still risky though, imo, so I'd say go with option A if you must still use a dildo while on your period.