Taking pictures wouldn't be illegal from a public place, similar to google's street view. Taking multiple pictures over a prolonged time could likely fall under harassment laws, depending on your state or country.
Videoing someone else's property, if done on purpose, is illegal, unless you have a valid reason for doing so. If your neighbour has 'violated the peace', IE noise disturbance (that you called the cops for) or something else but has been warned but not charged, then you can video tape someone else's property. If they're on the sexual offenders list or have a suspended sentence, or have been convicted of any crime that hasn't expired from their record. For example, your neighbour could have shoplifted, which IIRC stays on their record for 5-10 years after their punishment is served, you can legally record them (if you suspect them of other illegal activity, not because you're a pervert) until this time is spent. If you're recording them after this has expired, you're likely breaking the law and you're 100% open to a civil suit. However, if you have a neighbour you feel is dodgy, simply place a CCTV on your property to monitor a part of your property so it accidentally catches the other persons property (this has been proven legal in the UK, USA, CA, NZ and Australia, AFAIK). If you think your neighbour is doing something illegal in their back yard, but can't prove it, well you can legally video tape your back yard with a wide angle lens.
Audio recording someone else's conversation is definitely illegal; conversations are considered private, unless you're included in them. Public property is a different matter, but anywhere on private property is a crime, even if it is your private property, if the conversation doesn't include you it's still a crime.
Basically, if what you're photographing, and to some extent video taping and even less audio taping, what you could see or hear from the road if you stood there for 8 hours then that's legal. If you're purposely pointing the camera through windows, or any audio recording of their property, then you're getting yourself in a dangerous position. If your neighbour shouts and screams and can be heard on your property, that's legal to record.
Laws vary between countries, but generally if there's laws to protect you from the police doing said action, you definitely shouldn't be doing it. Also be careful, it can be illegal to photograph someone without their express permission, even on public property. I know a photographer got fined $1,000 here in Canada for photographing a girl in a bikini without asking. She told him to delete the photograph, he didn't. He was fined $1,000 by the police, and I believe she dropped civil action against him due to the police record, I think he was liable up to $25,000 in the small claims court she was taking him through.
So, personally, I wouldn't photograph something I don't own, or that no one owns. There's no sense putting yourself at risk for cash.
In this case, if the cops are just sat there in a surveillance van, not surveillancing anyone then it's legal. If they put it on a street with a known high crime rate, it's okay. If they put it on your street because of you, that's harassment.