The video gives you a step by step instruction how to replace the rear shock absorbers on your Audi 100/A6. The replacement is necessary when the absorbers loose their hydraulic fluid, you have problems driving the car, or you find places on the tire where the profile has vanished. Such a tire you'll see in the video.
The absorbers should be always replaced on both sides. To replace the front absorbers the same time is not necessary.
The video has a German soundtrack, but English subtitles are available by clicking on the "CC" to turn on YouTube's captions.