Best bitrate to responsive (web) video
Those are the expected file sizes for those data rates.  4 minutes and 42 seconds of video is 282 seconds of video, at 2.1 Mbps, that's 592.2 Mbits.  That's around 72 megabytes or so, so your 77.5 megabyte file is the correct size (there can be some variation and sound is also generally factored in separately.)

Those are also pretty close to the minimum bitrates that you can use without getting substantial quality loss.  2.1 Mbps is around the same bitrate that Hulu uses for their 720HD streaming and they are the lowest bandwidth of the major streaming sites that I'm aware of.

If you plan to host video, you really need more disk space and bandwidth.  Hosting is available very cheaply for multiple gigabytes of hosting space with unlimited bandwidth if you look around a bit, though I haven't been in that segment of the market for a while so I couldn't tell you who is best anymore.  (I self host on a dedicated server because I need a lot of space and high performance.)