It is not a software problem. It is hardware. The n900 today with various community dev contributions is a vastly more competent device than the one Nokia delivered. For example, the stock Nokia device was prone to slight pauses in recording video at stock (non-HD) resolution. However, it generally played non-HD videos well.

The n900 today can record at low-end HD, although the pause issue persists (some say it is due to limited RAM & io). The n900 today can play low-end HD, though after some time (and partic if you attempt too high-end HD) the dsp may become unstable and need a reboot. But it can do it.

Today I think owning and using the n900 is as much a matter of love and philosophy as it is one of owning a device (in the Android /IOS sense).

I understand your frustrations.