Whether it is surveillance by the state, corporations, or individuals, the issue (in my opinion) is not with the collection of data. It is with how the data is used.
Let's say that you were at a party and did something unbecoming, albeit still legal. Someone got a video of it, but no harm is done because the act and the video fade into a distant memory. Except that it doesn't disappear. Perhaps someone digs it up as a funny story, or because they're bitter about something you've done, or because there is some sort of way for them to benefit from the situation. Now you have people looking at something that is a snapshot in time that doesn't reflect who you are, or even who you were. Perhaps the video didn't capture the context, or maybe the context was removed from it. It has the potential to be damaging.
Actually, it can be more damaging than a video captured by a police or business surveillance camera. In many countries, the police have restrictions on how data is collected and handled. If it isn't being used for an investigation, they simply cannot disclose that information. If a case goes to court, you have an independent judiciary body examining it as evidence. Businesses don't have the same restrictions, but they can get themselves into legal hot water if they use or disclose data in an inappropriate manner. Contrast that to individuals, who are much less likely to be conscious of the boundaries between private and public information or who may not be thinking of the consequences of their actions. Unlike institutions, a lot of what they observe will simply end up as gossip.