I've been playing Sudokus for speed recently and I've begun recording my sessions. Originally I was just going to upload the runs for people to see, but they've actually served a much greater purpose. After just 2 days, I've increased my average time by a minute, which I attribute to watching my previous runs and seeing where I miss markings or more complex logical deductions. I then look more carefully for those particular types of deductions in future plays. If you are into playing sudokus for time, I encourage you to try recording yourself -- it's remarkable how much you can learn.
For those who care to watch, I have a video up here (Evil level sudoku in 4:05, no guessing). I'm sure some of you can complete evil websudokus faster, but it's still probably interesting to watch (and laugh at the blatantly obvious slots that I don't get until much later than I should, such as that 9 and that 5 :p). Unfortunately, even the evil level sudokus on websudoku usually don't require advanced techniques. I'd like to start making videos of even harder sudokus which actually require forced chains or colors to solve, and maybe overlay markings after the video is complete which explain the techniques used in real-time.
Again though, I stress that if you want to improve your times, I highly recommend you record your own sessions and then analyze them. More often than not, I find that any temporary halts in my progress are due to obvious slots (often simple naked or hidden singles) that could have been solved earlier on, which I now look more for whenever I play.
If people have faster times, I'd also love to see some recorded. It'd be interesting to see how much people's approaches vary and which misses people commonly make.
Edit: New personal best, 3 minutes and 46 seconds on Evil Sudoku Zero X
