In that case you're either getting double what you're paying for, or 1/4 of what you're paying for, depending on whether you're paying for 2MB/s or 2Mb/s. ISPs usually sell plans advertised in mb/s whereas your browser and Speedtest.net report in MB/s. One megabit (mb) is 1/8 of a megabyte (MB) so if you had a 2MB/s service, you would expect to see 2MB/s download, whereas if you had a 2mb/s service, you would expect to see 0.25MB/s download.
The above is somewhat unrelated to your problem, just something I wanted to point out. Either way, your speed sounds quite low for most videos, it may be that your cell phone is loading them at a lower resolution and/or quality and hence the low bandwidth isn't as much of a problem as on your PC.
