Why would something like Udemy need $1M investment? In a world where Django and Rails exist, etc. Just start building it and doing customer development bootstrapping it. Incrementally improve it as you go along. Keep all equity and maximize simplicity. If you don't want to spend money on a designer try to find one that will take equity. Exercise free promotion channels, also rely on word-of-mouth. Rinse, repeat.
They mention repeatedly the amount raised, I didn't see where it said at what valuation. If they were left with 75% of the company, that would have been a nice seed round. If they were left with 20% of the company, not so much.