Welcome to the forum, however, this should probably be in he Hardware Forum. Lot's of hardware gurus over there. One of the MOD's will probably move the post there, so if it seems to disappear, go to the Hardware Forum, to find it.
As for the RPM of the HDD's, that is their speed, in Revolutions per Minute. For Video, you WILL want 7200 RPM, as the minimum, to allow adequate transfer speed.
For RAID discussions (not likely in most laptops), see this ARTICLE.
Their downside is their price, and their power consumption, but then they can be adapted (Sager does more gaming laptops, but they adapt well) for video-editing.
You need at least two 7200 RPM SATA disks or better even three.
Video editing entails lots of traffic. Lots of traffic on a 6-lane highway goes pretty fast. The same traffic on a single lane road is damned slow, with traffic lights allowing traffic from one direction only at a time. That causes traffic jams. Laptops entail real slowdowns over desktops. With only one slow disk it will be slower than molasses in winter. Like an elderly snail hitting the brakes before cornering.
Consider a 5400 RPM disk as a car with a top speed of 54 MPH, a 7200 RPM disk as a car with a top speed of 72 MPH.
Moved to Hardware forum