Blur Busters browser tests have shown Chrome, Internet Explorer 10+ and FireFox 25+ can play 120fps video in real-time! This video is a true 120fps real-time video, not slow motion. You must use a 120Hz monitor and a recent nVidia/ATI GPU to view this video at full frame rate.
Cameras capable of 120fps can be obtained for under $200, including Casio EX-FC200S. A better model is GoPro Hero 3, which can capture 120fps in high definition 1280x720p. Usually, 120fps is “slo-mo”, but can be sped-up to real-time playback on 120Hz monitors.
For instructions, see article 120fps Web Video In Real-Time on how to create such videos.
EDIT: For a 1080p embedded video at 120 frames per second, see the newer article.