Don't have any suggestions, but I do a number of shoot videos a year and post on YouTube.
Under $500 will bring limitations.
I don't find much use for built in memory so you may be able to purchase a better camera with funds available without same. Use memory cards and just insert into computer for editing.
HD is a must.
If you can find something that shoots more than 30fps it will help with slow motion shots.
The small cameras are hard to steady. Tri Pod needed (a good one). If the tri pod is to lite, on windy days the wind will push it around.
The smaller cameras have wind sound issues, so you always have to be thinking of your camera setup on windy days. You may want a camera where you can install a mike with a wind filter. Some of the smaller cameras don't have that option.