Just in case any of you are interested... Here is the my quintet playing Brahms a few weekends ago. This is the first time that we have played together, and the first time we have performed together. The Brahms quintet in F minor is an amazing piece (we are playing just the first movement). I think that we did fairly well for just a short amount of practice time. (Keep in mind that we are just amateurs--people who simply play for the love of the music... we are not the Emerson String Quartet--that is my tender vulnerability coming out...)
As you are watching, notice how we play off of one another. Try to trace how the melody moves from instrument to instrument. How does the piano interact with the string quartet? How do the string players interact with the piano and with one another? Sometimes we literally pass the tune on to the next player. Sometimes we are all playing the tune together. Other times we support another player, helping them to soar beautifully. In a few sections we are all playing at different times, playing just two or three notes of the tune, playing off of one another to make a unified melody. I hope you enjoy!
Regardless, you just gotta love Brahms...