I've done this before. Just add an annotation.
Be prepared to have endless comments about it from mobile users though who cant see it.
Side note, I checked out your channel. It's a really cool concept, and your branding is sweet.
One big reccomendation though: I would cut to the chase much faster in your videos. I watched a couple of them (the one about jersey and the tsanami), and it was well over a minute with each of them before I even started to know what I was watching. Grab your viewers attention fast, and you'll see better audience retention. Tease them with something crazy or at least pitch the value of your video at the very very beginning.
It's obvious you're putting a lot of time into editing each video, and this would be my tip that might help you get more people seeing that hard work.
cheers mate.