I'm using a 128 Mb Ramdisk for ages now.
I can't compare the speeds, because HDD are so fast, but anyway it makes sens to put all temporary datas and make all useless operation requiring to write on disk on a ramdisk in order to spare HDD resource availability and longevity.
The more you use the Ramdisk the longer your HDD will last. Here again I have no scientific comparison to support that but it's logical.
There are so many actions that put garbage on your HDD that it makes sens to put all of them on a temporary Ramdisk.
I set all the "temp" files and folders on the Ramdisk.
I'm also using the Ramdisk for the IE cache (temporary internet files).
As for reading videos, it's certainly a little bit faster than HDD but I doubt it would make a noticeable difference unless your HDD is old. At 5200 rpm, it should make no difference unless the HDD is busy doing something else, which is also a good reason to use a Ramdisk.
The other problem with Ramdisk is that it's erased everytime you turn off the computer. So any video to be played off the Ramdisk, will have to be copied first from the HDD to the Ramdisk. And this will take a lot of time.
Unless it's a video meant to be replayed many times during a single session, this is not an efficient solution.
One can imagine using Ramdisk to loop-play adds on screen in a shop, or to replay endlessly your favorite music (meditation mantra would be perfect for that usage -LOL-)
Some members here use the Ramdisk as a location for the swap files (which fills when the ram memory is full).
This useful only when the physical memory available exceeds what is supported by Windows 98, even patched, and when the Ramdisk is large enough for that purpose.
Idealy, one could think of a setup where all files and temp files which has to be constantly rewritten by the system itself (eg: user.dat) are located on a Ramdrive.
Not running windows off the Ramdisk, but copying and using all files to be often modified there.
That way you could work with drive C on iddle mode.
Imagine the disk usage saving!
But I don't know if it's possible. Nice testing experience here!
Edited by Fredledingue, 28 February 2012 - 05:22 PM.