If you want to improve your video results, look to these microphones I personally own. All of them provide excellent results for the investment, and will improve the results of your video when you need to do voice-overs.
Audio is half the equation in video production, and great audio adds credibility, understandability, and power to your video productions. A good production environment (no background noise, good acoustics, helps too. But without starting with a strong voiceover, you're hurting the impact your video will have. A good microphone gives you ahead start towards success.
These choices are ones I've purchased myself. They are in a range of prices, but none to crazy. Even the most affordable among them will do the job. They will vary slightly in characteristics, but all good editing programs give you the chance to "sweeten" the sound with equalization. Some will require "phantom power" to really do the job; others use a direct connection to USB to skip that need and connect directly to your computer. Some people like going direct to computer, and some like going directly to a recording device. Some recorders accept minjacks; others require XLR inputs (the sign of needing phantom power, which means those recorders have that built in. Here's the list.