Go in to a local city or a shopping centre (mall for the US folks) and just open up your camera and record back to back of you talking about random stuff. You can delete these videos at the end so it doesn't matter how good they come out, or what you say in them, this is just for practice to warm you up and get you more familiar with it. Keep doing that in little short 5-10 minute film segments until either it's time to head home, your camera SD card is full, or your battery dies.
Now go home, charge your camera up again, and copy just the first and last film you made off the camera. Now look at the difference in how confident and relaxed you seemed on camera after just a few videos, compared to that first video. After making a bunch you should naturally find it a lot easier to do again next time, but if you do struggle, just use this trick again and film a warm up video or two, then delete those and film your real one.
Recording yourself in public is a bit like public speaking or even just socialising in an unfamiliar environment/with unfamiliar people. It starts off nerve-wracking to some degree for everyone even if you're pretty confident, but then after a few minutes you're fairly relaxed, and after 10-15 minutes you completely forget you were nervous in the first place because you're too into it. So warming up can be great for that.
