There is absolutely no way to convert a video and retain 100% of the quality. I did a post a few years back explaining the reason why this is the case. But, in a nutshell, video codecs such as MPEG, Flash, etc., are lossy formats. This means that every time you convert a video, there will be quality loss. Flash is a very poor retainer of video quality (even at high bit rates such as what you set). Most popular sites that wish to better maintain quality use H.264, which is still a lossy format, but has the ability to retain video quality much better at much smaller bit rates (which is partly the reason why H.264 is used for HD video on just about every website and even on Blu-ray discs). If you are really concerned about maintaining a quality level that is as close to the original source video as possible, you may want to consider using H.264 instead of flash.