Let us not forget that, if you are claiming these videos show evidence of alien life visiting the earth, then the burden is on YOU to show why no other conclusion is logical. This is the biggest mistake that fringe/conspiracy theorists fall prey to: They are LAZY. You cannot simply throw out videos that you believe look anomalous, and then expect those who spent more time studying science than you to "debunk" your belief. You need to establish your belief as something more than just a belief. So please get on-board with real science and understand that if you are claiming something is so, YOU have a lot of work to do to establish that it cannot be anything else.
Now, as to the videos: At LEAST 5 out of the 6 videos on your list can all be explained by the very nature of the gravity-free (or very low gravity) environment of outer space where there is also no air resistance. In other words, 5 of the 6 videos can be explained by what we know of orbital dynamics and that even includes the one where you say the "object did a 90 degree turn." If you look at that video a bit more closely, you can see that the object that eventually makes a "sharp turn" and heads AWAY from earth is also on a collison course with another object. Look closely and you will see the main object and another point of light converge on the same spot, and THAT is when you see the main point of light move up and away very quickly. This is a very rare moment captured on video to be sure, since it is not often things collide in orbit and a camera is there to catch them. But that is exactly what happened, and the dynamics of the motion post-impact even help validate that this is what happened: You will note that after the collision the object assumes a great deal of the momentum of the object that it struck: THis is why is moves in the other direction and so quickly. I can also predict that the other object had a mass at least twice as large (or was going twice as fast) as the object you see moving towards the earth. The other typical thing you can notice is that there is a net deceleration of the object's velocity right after the impact. Immediately after the impact, the object is moving its fastest, and as it moves away from the earth you can visually see it slow down (decelerate). This is EXACTLY what you would expect by Newton's F=ma as well as his more general equation for the gravitational attraction between two bodies. The gravity of the earth (MUCH larger) is acting to arrest the acceleration of the object caused by the collision.
One of the other videos shows a satellite being released from the space shuttle cargo bay. The person who made the video seems to think all he needs to do to present his "evidence" is to circle a bunch of small dots of light and his case for "aliens in UFOs" is done. Not a chance. Notice that every single one of those dots of light is exhibiting uniform motion AWAY from the shuttle bay. These are most likely small bits of dust and debris that are floating out of the shuttle bay. And YES even small bits of dust will get lit-up not only because of the sun's radiance but also because of the velocity these bits of dust are traveling (at least 11,000 Kilometers/hour which is orbital velocity!). While they try to keep the shuttle as clean as possible when mating it and loading-up the crew and payload, the fact is there are still MILLIONS of little dust specs and other small objects that float around once they get to zero gravity. And given that the space shuttle is receding from an object it is releasing from its cargo bay (it does not "shoot them out" with a rocket...rather, it releases them and then changes the motion of the shuttle to move away from it) then it only makes sense that all those little pieces of debris and dust will move away from the shuttle as well (in UNIFORM MOTION!)
So there... I have "debunked" at least two SPECIFIC cases from your 6 videos above. Some of the other ones are so silly (and NOT evidence of intelligent life) that they do not even deserve mention. But let's remember that if you (or the maker of this video) is making a claim that this is evidence of aliens, you and they have a LOT further to go. Please do not forget that a "real scientist" will always TRY to falsify their theories/claims when they make them. They don't throw out questionable evidence (which can be explained by other, more mundane effects) and then lazily wait for someone to debunk them. They do enough up-front science to SHOW they have considered the mundane and ruled it out (with the science and math quoted to show they considered it and why they rejected it).
