This all really depends on how you plan to use Moodle how many users will truly be simultaneous. You mention that you are going to use Akaimai but that could be irrelevant. Your statement "so the users will be watching it through there" makes it sound like you are using Moodle as some sort of frontend to deliver video content. While you might be able to serve the video content with ease, the Moodle site will still need to generate dynamic content which is what will be your bottleneck. The more Moodlely bits you have enabled, the greater the challenge will be. If you are truly just delivering video without the need for the learning, then I'd suggest you find a different platform for your task.
If you have the money for Akaimai and you really do hit 100,000 - or even 20,000 for that matter - potential active users, it might be worthwhile paying some consulting fees to talk to someone who is familiar supporting a large Moodle installation. You dont want to risk your company's reputation because you went off some generic information in these forums. The conversation you need to have goes beyond just making sure you have enough ram and cpu. You will need a sufficiently sized db, a performant IO system, monitoring, failover, caching (as Howard mentioned - its a must have), and probably most importantly, how you've setup your Moodle site.
Another thing to consider would be to see how people interact with your existing company website. Do you get a flood of activity at certain points during the day? (i.e. Right after an infomercial is shown, just airing, etc) Consistent traffic throughout the day and night? I mention this because it might be deterministic of how your Moodle traffic will look once you go live.