(There's no video for FakeNES yet. Please contribute to MR and add a video now!)
FakeNES is a portable, Open Source Nintendo emulator. It uses the Allegro library for input, graphics, and sound across various platforms. FakeNES is written in 100% C language code. This makes it very portable, but also very slow compared to many other NES/Famicom emulators. OpenGL is supported, through AllegroGL. For best results, disable any "enhancements" that your video drivers may force upon the program.
FakeNES-0-5-8.dmg (2.04 MiB / 2.14 MB)
FakeNES v0.5.8 / DMG image
Mac OS X
Emulating this? It should run fine under: QEMU