Thanks Dude! The acid solution using oxalic acid is not strong enough to burn through the skin by touching it.  Although it may cause irritation or damage if I just left the solution on my hands for long time.  As long as you are careful to rinse your hand thoroughly if you come in contact with it, then you'll be fine.  But you're right, I should probably demonstrate more caution especially when making an educational video about how to use it.