Samsung has uploaded a few videos on the Samsung GALAXY S5, Samsung Gear 2 and Samsung Gear Fit. Instead of just introductory video, Samsung has put in the effort to do a very professional hands-on on these devices.
In these videos, you can see the devices in action. However, since this is a Samsung video, things that you hear from the usual hands-on video will be missing. For example, on the Gear 2, it is mentioned that the battery life has improved 3 times. It may seems a big improvement. However, if you know Samsung Gear, it has only 1 day of battery life. With 3 times improvement for Gear 2, it means that it only last 3 days.
Other than that, they are very well-produced video.
Samsung Gear 2 and Gear Fit
Samsung GALAXY S5