Would it be possible to play a blu-ray dvd on ps3 and record it with a DVD recorder?

No. While you could physically connect a blu-ray player to the inputs of a DVD recorder, you wouldn't be able to record a useable picture. This is because the blu-ray player still uses macrovision (a form of copy protection), and the DVD recorder will scramble the incoming signal so you cannot watch, much less record, the movie. Even if you could record a blu-ray movie in this manner, you wouldn't even get DVD quality.

You would be able to record, but i don't know how much. If you put the output from the PS3 to the DVD recorder, the recorder will record what ever is sent through it, but I don't know if it would record correctly or the full amount. The Blu ray is going to send more information as it is high def, and they can hold up 50 times the amount of data as a DVD. So it may be that it will record only a portion before it fills the DVD..