Todo:

show time elapsed
print the performance graph as well to see perfromance difference, using different number of threads and
show progress
also need support for google-drive, dropbox, a simple youtube version too.
use interactive terminal to show progress across each thread, so it more cooler
upload it to free file sharing service upto some MB, you can build one for yourself and share it with others, write in go, or node js and also use it here, a simple service the life of the service can be just 1 hour, there you can learn so many interesting things
download files after giving username and password(with authentication)
export as package too, later somehow
show current download speed and ETA (ETA depends on the number of threads, download speed, speed of server)
maintain history of downloads, if there is a flag -h = true
Bugs:
Handle the case where there is no internet
while downloading file if there is interruption and if the downloaded file is incomplete, what will you do, you can find out incomplete file download by checking expected bytes to be written and bytes written, and then you can try to retry that attempt
even if the program crashes, use exception handling and restart the download with same thread count
Create a ruby server and try to serve a 10 gb file and try to do the same in go and other servers and estimate performance and also node js

Help wanted: