I just got a base 13" MBP (2010 model) from MicroCenter last week and noticed problems streaming Flash content on YouTube. I can get the first 25% of the vid downloaded quickly and then it hangs and buffers.
I have Fios service and results from Speedtest & Speakeasy varies between 15mb/s to 25mb/s down / 15mb/s to 20mb/s up. I have PC laptop (Sony VAIO CW i3 w/ Nvidia 310m) that can stream the same video quickly and smoothly without having to buffer.
I've tried both hardwire and wireless connections. Both connections are an issue w/ my MBP. Browsing with Safari 5 and Chrome 6 Any suggestions other than re-installing flash?
This is the video that I've used to test and my MBP hiccups all the time.
http://www.youtube.com/watch?v=Fcfi-ji8S7I
EDIT: Lags for both SD and HD content.