I wrote to a web designer friend of mine and got some suggestions and ran some more tests using the link that always shows this issue on my 10.6.4 Snow Leopard system running Safari 5.0. FlashPlayer plug-in is version: 10.1 r53.
http://latimesblogs.latimes.com/technology/2010/06/iphone-4-review.html
I just went through the four "web content" choices in Safari 5.0 under the "Security" prefs tab. The only one that toggles this behavior is the first item called "Enable plug-ins". With "enable plug-ins" set to OFF, the offending web page loads, and the mouse cursor is fine, but the top of the page is missing the video, large white space holder is seen. I asked him what kind of video link it was, and he responded: "The main video, the banner ad and 2 sidebar ads are all in Flash. One way I know that is that I use ClicktoFlash".
In his next message a few minutes later, he tried that same page, running the same software, and it CRASHED his Safari app. He said he did NOT lose the cursor, but the effect was the same.
His last comments were:
"They have more junk on that page than you can shake a stick at. Safari crashed a few more times too. Flash is a plugin which is why you see the blank box. I would say a lot of this problem is all the non standard crap the LA Times is using for marketing, advertising, tracking while they slowly drown."
So it's possible that Flash Player content is one culprit perhaps combined with bad HTML code writing on certain web pages. Try changing the "plug-in" settings I described above in both Safari and Chrome to see my findings, (NOTE: I do not have Chrome installed here).
It would be useful to have some more links that exhibit this behavior posted here. Anyone?