It been a long time since YouTube introduced mobile version of its website. I remember I had some trouble opening the videos with my Dopod D810 when I first tried it. I did not put much effort to make it work at that time.
Today, I'll spend some time to make it work. After some trial-and-errors, with the help of Google search, here are my findings on why my Windows Mobile 6 can't play the videos on YouTube and how I finally managed to do it.
My PDA is connected to internet via wifi (not 3G or any other direct connection to internet). It has Streaming Media application preinstalled, that comes with HTC ROM.
After clicking on "Watch Video" in YouTube mobile, the Streaming Media program launched and instantly get rejected with "Failed to connect." error.
This can simply be fixed by selecting the right connection. It can be done by opening up the Streaming Media application, click on Menu > Options. Select the right connection at "Connect via". If you were to use wireless LAN connection like me, you should be choosing "The Internet".
After clicking on "Watch Video", the Streaming Media program launched and tries to connect, then it failed with "Failed to find network" error.
From xda-developer forum, I understand that to make the Streaming Media program work, we need to make the device directly connected to internet, and not connected to internet via a router. (So, I think those who connect to internet via 3G, EDGE or GPRS should not get this problem)
This problem could be fixed by configuring my mobile device to be in DMZ zone, but this is not advisable due to security issues since you are exposing all ports of your device to the internet. However, it certainly worth a try to know whether it works this way. And, I did try to configure my Dlink router and get the YouTube videos playing properly in my PDA.
I tried to reduce the number of UDP ports configured in Options of Streaming Media. I configured it range to become 1024 to 2048, allowing only 1024 ports. Then, I fix the IP of my device and port forwarding those ports to my PDA. And I got the videos playing properly. Again, please be reminded that there could also be security issues when you do this, but at least, you are not exposing all the port of your device to the internet.
I guess there is no other options. Please comment if you have any better ways.