In the current version of the Mozilla Firefox web browser (version 2.0.0.12 at the time of this writing), the memory usage is a problem whenever you visit flash-intensive web sites. Mozilla themselves has admitted this. In the current beta version of Firefox 3 there is an add-on called RAMBack that supposedly cures (most of) the FF memory leak issues. I have not tested this as of yet but plan on doing so.
To see an example of the memory leak problems with the current Firefox 2, see video below.
This is a problem with Firefox, but actually your video barely scratches the surface. After using Firefox daily in my routine work on Windows, I routinely see Firefox using up over 300 MB of memory. As I type this on my Mac Pro, Firefox is using 251 MB of memory under OS X. Granted I haven’t closed the browser in 2-3 days, but it still is a beast.
I can do better than that. Stock FF (no plugins etc) consumes more than a gig of memory according to task manager with Marketwatch, Bigcharts, Ebay, 3 search pages on ebay after 2-3 days. I believe Marketwatch may be the cause for the bulk of the problems as it updates itself every couple of minutes. But over a gig come on. Restarting with the same tabs results in 90-110mb. So there is 900mb of waste here and with that much it slows down not only the browser but my system as well.