The industry standard definition of internet speed is “megabits” (MBps) per second, which doesnt actually exist. The actual speed is measured in MB/sec (megabytes per second).
To convert a megabit to a megabyte, you divide the megabit by 8 (as there are 8 bits in a byte).
In essence, your 2megabit upload, is actually 0.25 megabytes per second, so your connection can only upload 25 kilobytes per second (KB/s), which when your talking about a film (usually 1 or 2 GB), will take a very long time, hence the constant buffering.
I have the same issue as you, and im thinking about increasing my broadband to cope with this to a speed with 2.25 megabytes per second (18megabits).
To improve the speed inside your network, upgrade your router to a gigabit router, and if your streaming over wifi, use 5GHz instead of 2.4GHz.