Might check to see if differences in length, resolution, etc of videos #1-#4 affect things.
Are there observable differences in how the videos are being cached on either computer?
You may also wish to see if other videos that don't use YT player show differences in non-WiFi v. WiFi playback on your two computers.
Also, if feasible, it might be interesting to see what happens if you switch the two computers around in your network...e.g. if the problem follows the computer (nothing changes) or follows the network position, or even if it becomes worse or disappears.
More YouTube operational oddities...
Something else I just noticed about YouTube's recently changed operations...you may remember I commented in your earlier thread about YT's no longer creating xxxxx.flv files for resolutions lower than 720p?....Well, I wasn't thorough enough.
I found out that if you start a 480 video, then change resolution to 360, then change back to 480 it will create the xxxxx.tmp file. Similarly, if the video defaults to 480 (which apparently doesn't create the xxxxx.tmp file) when you first start playing it, but change to 720 or 1080, it will create a xxxxx.tmp file. However, I couldn't find a way to make YT create a xxxxx.tmp file for any videos that came in ONLY 240 resolution...because there's no way to switch resolutions.
So definitely odd stuff going on with how YT caches videos on the computer...which may affect WiFi bandwidth requirements, etc. Just speculation.
I made my this latest observation on only a single computer using 32bit Windows, Firefox 3.6. YT may do things even more weird on other platforms/YT versions, plug-ins, etc.
By the way, if one has an SSD and use programs a lot that heavily use the
C:\Documents and Settings\userid\Local Settings\Temp\
one might consider to move that folder to a mechanical HDD to reduce write operations on the SSD. Similar thing with the pagefile...of course there may be an impact on performance that may need to be balanced with the impact on SSD life. Also, I think decreasing the "real-time" heavy usage on an SSD may help reduce
the BSODs and occasional turning SSDs into bricks that many people report on various websites (Just a couple of the reasons I like to know which programs are doing what with the filesystem.)
If one does decide to move the folders/pagefile to a different drive, then it would be a good idea to reference my post on the major
difference in performance made by where
you put the folders/pagefile http://www.hardwareanalysis.com/content/topic/77420/#590037
(for example, to get the best performance out of using a mechanical HDD, I'd create a "just big enough" first partition in a high-performance HDD for either the pagefile or the temp folder, and if I moved both, I'd put them on different HDDs (not just different partitions)).
edit: added the bit about switching the two computers' places in the network
added the reference on partition size&placement on HDD performance impact