Here, speedtest (image 1) says 1.7mbp/s and when downloading something, I get about 100-200kbp/s... (image 2)

http://imgur.com/a/lo1fx (2 images)

Why?

 

Some sources throttle you HARD.

Try downloading the same file from 2 different sources at once (DownThemAll supports this) or using multithreaded downloaders (again, DTA).

 

There are two reasons, your download speed the browser is reporting is in bytes as Armadillo suggested and speedtest is in bits (divide bits by 8 to get bytes).

The other reason if you are getting a slower download speed is that the server cannot manage the bandwidth at the moment.