It's not related to TV out at all, the N900 suffers badly from tearing (scroll the home screen slowly and you'll see horizontal bands where 2 frames are intermixed and various other jittery movement). And as I said in the first post the test was to see if the GPU is waiting for the next frame before putting out a new one to the screen.
It isn't.

This is how it works (conceptually): the TFT monitor pulls pixels from the framebuffer in the VRAM. It should not do this while a program is rendering into that memory/buffer, so you double buffer and send whole frames. In code - the action where you swap buffers should wait for the GPU to finish its work to keep in sync with the signal to the screen, now it doesn't, this should be solved in the driver. Nokia's official response was "we don't care" a while back.

In this (digital) case it's about 2 chips fighting over the same RAM.

This issue is related to iphone and HTC android phones because they have it which the N900 doesn't hence the N900 is shunning developers away.

One analogy: It feels like someone is taking your artwork and running it thorugh a paper shredder then taping it back together.

You can get vsync tearing on a PC with a TFT monitor if you turn off vsync in your drivers.