Grammar, Usage / Grammatical errors in this sentence [15]

"Finally, after analysing the questionnaire and interview data, we summarize the elements of video that test-takers really pay attention to and the functions of those elements."

Perhaps one of the following - in my opinion:
1/ summarized:
2/ elements of a video: in case you're mentioning a random video, the indefinite article is needed ("the" if it is a particular video)