Depending on network speed, a fast start QuickTime file can be played almost immediately after the page is loaded. As long as the user's connection is faster than the movie's data rate, the movie will play from start to finish without pause. The implication of fast-start video is that duration is no longer an overriding concern for audio and video site content. At one level, it no longer matters if your video is one minute or 10, because with fast start each of these durations look essentially the same. As long as the user's connection and the movie's data rate are within the same range, your one minute movie can start playing at the same time as your 10 minute movie.
File size is, of course, still a consideration.
A 6MB movie file needs to be kept somewhere on the client machine. Some machines will crash if asked to hang onto large movie files. Assess your audience their network access, their processing power and memory configuration and plan accordingly. For example, if you have 10 minutes of video that you want to put on the web for low-end machines, chop it up into smaller chunks to make sure your audience can access it. Data rate limits Set the data rate of your movies slightly lower than the throughput of your user's connection is you want them to be able to watch your movies in real time.