The stuff people find to worry about!
Even if it was illegal to do so (which I strongly doubt), the likelihood that you'd get a ticket for it is basically zero.
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Originally Posted by
pdlamb
...there's a possibility that anything on a helmet could hurt you...
A manufacturer (or the guy in the video) has no idea what people are considering attaching to their helmets. It's much easier/safer for them to say "don't do it" than it is to keep the issue open.