How to shadow?
Repeat each line after the speaker; you will have several seconds to do so. Try to match the rhythm, syllable stress, prominence, and intonation of the original recording, while following the visual cues. See How to Practice? for an explanation of transcript markings.
For best results, shadow the video every day for a couple of weeks. If possible, record yourself and compare your pronunciation, or send the recording to your English pronunciation teacher.