your memory speed might be too low, and while watching a video it would go from idle to a higher clock. Probably the higher clock is giving you a better hashrate. Try raising your memory clock 50-100 Mhz. Also, most pools seem to use pushpoold, and if configured decently stales are usually less than 1%. Good luck on figuring out how to configure it though. If you're going to manually set the askrate, I'd suggest setting it to 100 and the queue to 4.
I'll try that, thanks.
Also, I thought with solo mining you don't get any stale rates since it's solo..
Well, if the server/daemon doesn't tell the mining software that a new block was found, it'll be working on stale data.