Ecliptic Enterprises makes a series of rugged little videocameras that can handle the stresses of launch. The Ariane booster containing Sentinel-1A had a couple of them on-board and they returned this terrific footage of the launch, solid-rocket ejection, fairing release, and spacecraft separation. The time index in the lower-right-hand corner shows that the video is speeded up in general, more in some places than others.
Ecliptic has a YouTube channel with more. One of my favorites is of the 2001 launch of the Mars Odyssey mission. This is older RocketCam technology but towards the end it shows the payload being spun up prior to release. This is not usually done but was required for this mission’s objectives. It’s still in orbit around Mars and still working.