It would be presumptuous to believe that we are the only planet in the whole universe that has managed to bear life. There are other solar systems such as ours, there are other planets that seem to be as ours, and comets have probably also hit it, bringing in the necessary ingredients for life (or eradicating it).

So yeah, there are probably other lifeforms out there. But assuming that they can travel across galaxies and visit us, assuming any of the footage on YouTube is true, assuming that there are "Visitors" among us, without anyone knowing (for crying out loud, we can't even keep government secrets without forgetting them on the train) is a bit pushing the envelope.

First of all, why? Why would any race bother with visiting us, without making contact? One can only assume that most probably, other civilised societies also have ideas such as money, and limited resources (so that they need to prioritise). So, creating a vessel and sending it half way across the universe to visit us seems highly improbably for recreational use. So scientific maybe? Sure, but what are they getting from it? If they are so advanced, then they most probably aren't learning that much from us (having made the same mistakes a long, long time ago).

Maybe they are in contact with our governments? Sure, but again, what are they exchanging? Do we have anything of value to offer? If so, how come nobody knows about it? UFOlogists only talk about people being taken and having implants, if there was any truth to a government-conspiracy, then surely it would be all over the tin-foil-hat forums?

There is one, much more plausible explanation. If we ever have visitors knocking on our door, it'll be because we're either a/ food, b/ sitting on a planet they could use because they destroyed theirs. We'd get nuked from outer orbit without ever having a chance to reply, and that'd be the end of it. What? They're aliens, so they're not capable of such madness? We did it, time and time again. Whites did it with blacks, indians; well, anything that wasn't white.

Again, as I quite often come to say: Stupid men are way too arrogant, think they're way too important. We're not important to a species that has involved travel across galaxies, we're not even remotely interesting. Our planet is very, very specific. It's also quite preposterous to believe that their life-form would be compatible with our planet.

Edit: To sum it up: Life out There? Yes. UFOs? No.