There are two different versions of the score you see on the Video watch page on YouTube:

General Version- If it's a video where we don't know the Target Keyword, we show a general SEO Score. You'll see this version for videos belonging to other channels or videos of yours where an SEO Studio optimization hasn't been applied. If you hover over the score, you'll see a breakdown similar to the one below for this general version.

SEO Studio Version- If it's one of your videos that you've applied an SEO Studio optimization to, you should see the SEO Studio score version since we know the Target Keyword because there's an optimization tied to the video. The SEO Studio score version breakdown should look similar to the one below if you hover over it.