Svoberts, unfortunately you won't find any attorney to do this type case on a contingency. They cost too much, no insurance company to pay for it, and settlements are in the low 5 figure ranges for ACTUAL damages only without even legal fee recovery. These are lose-lose-lose cases.
H2a, if the video does indeed show damages actually being done (ie ditches being formed/caving in) and intentional tresspass, Then the "one and only" lawyer is an absolute idiot! Go talk to many attorneys, it will takes years to get to court and settle this. You will end up spending more on the suit than you will on repairs though---very very sad, but very very true.
We understand how angry you are about this and we are too, but when it comes to a court, anger makes your petition almost worthless, courts only deal with facts.
Now for a dose of reality, If the damages result in a dirty pond that will clear on it's own in a few weeks and there are no fish killed, as a matter of law, there are NO damages to recover. That is what is so bad about this type of problem, there are really no punitive damage that will be awarded unless you take them to court many, MANY times, at your own expense.