Originally Posted by RabidDog
He did say editing HD video ... editing is a hands-on task, encoding/transcoding can be left to run overnite or all weekend. So speed in the editing part will be most felt. possibly not raid but certainly a fast hard disk 7200 rather than 5400 or even 4200, with loads of ram 4gb
Editing by nature requires scanning the file (scrubbing the timeline) to find an edit point. Since HD video is highly compressed, decode is necessary to view the edit search. This is all CPU (with GPU assist) and has little to do with disc access speed. As said above, typical 1x HD playback is 8-30 Megabits per second (1-4MB/s). A typical laptop drive can handle 5-10x that and a 7200 RPM SATA drive can handle 15-20x+. Even when only I frames are being read, the CPU/GPU is still the bottle neck.

Only exception is when the disk drive gets extremely fragmented (e.g. when almost full) then slow disk seeks become the bottle neck.