One of the big challenges with Video SEO is tracking how your videos are appearing in search results. You can do this manually by searching with relevant keywords and noting where your videos show up - but that's a pretty tedious process.
An easier alternative is to use the Moz Keyword Tool. This handy little tool aggregates all your keywords in one place and shows which are yielding video results (in addition to standard page results). And as a bonus, it updates weekly so you can see how your rankings change over time!