Fx3.5 & Fx3.6 & video flash in the web

[gatolandia.chile]

I'm stuck with a problem playing video in the web in sites like youtube,
etc.

I have Fx3.5 and Fx3.6 installed, each with their separate profile and
with the same extensions in both, with Fx3.5 having a lot of more
extensions than Fx3.6

When i play a video in Fx3.5 the video make use of the full speed to go
in advance(buffer a lot of the video), usually the video is "downloaded"
full before minutes of playing( if the video lenght 5 minutes. the
full vide is disponible around 1 minute of playing, other videos will be
speeddown).

If Fx3.6 the EXACT same video is only buffered in advance around 20
seconds or less

WindowsXP SP3

[gatolandia.chile]