Hardware :: Video Streaming Set Up ?

The set up:
iMac (early 2009) ethernet connection to TimeCapsule
iMac is running Medialink
TimeCapsule has a folder with MP4 movies of varying bitrates/quality
TimeCapsule is the internet router
PS3, connected through 802.11g wifi for internet and media access
Macbook air, connected through 802.11n for internet and media access

What works: Netflix streaming in my PS3 works splendidly, including all HD content (720p) at data rates of around 5 MBPS

What does not: Streaming movies from Airport disk to PS3 is awfully jerky and stuttering for all decent quality rips (i.e. 1.5MPBS and more). Low quality rips, 700KBPS or below, play alright as far as I can tell. Thought perhaps PS3 is not playing well with the all mac set up, but streaming the content to my macbook air is also the same way. Unusable.

I do not understand why despite having faster connections on both ends (802.11n to n), I can't stream playable content at 1.5 MBPS on my network (points to some upload issue with TimeCapsule?)

On the other hand, despite slower wifi, PS3 is able to pull content from the internet via the same TimeCapsule, even HD movies, and plays them smoothly.