It would be best if there's some application/website that can make comparing 2 videos easier, instead of switching between different 2 tabs or resizing & putting 2 different browsers side by side.
A google search brings me to YouTube Doubler.
Just copy & paste the url of the videos, and YouTube Doubler automatically picks up the embed code of the videos and align them next to each other, IN THE SAME WINDOW!
It loads and plays both videos automatically, allowing us to simultaneously compare the videos.
It's simple to use, & no registration is needed.
A click on 'Put on your site' under the video generates the embed code for us to put both videos in our own website, like the one below.
Note: videos resized to fit the width of my blog.
Pretty cool eh, just making use of some simple logic and it saves us a lot of hassle.