NESguide.com is in the process of archiving gameplay video for every one of the 766 games released commercially in the US for the Nintendo Entertainment System (NES), including recent homebrews. All videos are captured directly from actual NES hardware and cartridges, as opposed to software-based emulators which (in most cases) are not faithful to the original hardware experience. In other words, the video and audio are true to what you would expect out of your own NES if you had the actual game paks in your system. There is no commentary to bias your impressions of the games or drown out the classic 8-bit sounds and music, nor are there any video edits which would misrepresent the flow of play; the videos are all in real-time. These videos are purely for archival purposes and are not intended as skill demos or walkthroughs.

If you're looking for SNES videos, check out SNESguide.com or youtube channel: snesguide1