OK, fair enough but I would suggest strongly that you find a WISP rather than use Mobile Broadband.
That tip in the YouTube video is worth 20%.
You need to see what your signal strength actually is so you can see if you have increased it when you try various things. A USB cable has a length limit before it stops working. It's not very far USB extension cables give you a lot more but they are still limited.
You may want to consider a FON router;
This gives you three valuable benefits. First it will accept your 3G dongle so you can place the device where your 3G signal is best without needing a massively long USB cable.
Second, it gives you a WiFi router to which you can connect your laptop and other WiFi gadgets.
Finally you get a FON account which in many countries provides free unlimited hotspot access so you can cane someone else broadband rather than your 3G.
The downside is that someone can use your 3G connection, but you have some control and the chances are pretty slim. No one has used my FON hotspot.
Wayland - Anglian Rural Broadband
Connecting you to 2meg or more in rural Essex
Home ADSL connection: