Nobody seems to know what obstruction is, or at least the TV announcers in these videos do not know. They all say "interference", but these are all examples of Obstruction.
Obstruction is simply a fielder without the ball (or not in the act of fielding the ball) getting in the way of a basebunner, which rarely happens in an MLB game, but it happens all the time in Little League. There are two types of obstruction, Type A & Type B, below are MLB examples of both types.
Type A Obstruction occurs when a play is being made on the runner being obstructed.
Type A Obstruction by First baseman. Immediate dead-ball, runner given first. P and 1B cannot both be in the act of fielding the ball. Since 1B didn't have ball he was guilty of Obstruction for being in the runners way.
Type A Obstruction by Third Baseman during a rundown. Immediate dead ball, obstructed runner given next base. Only a fielder with the ball is allowed to block the path of the runner during a rundown. The obstructed runner is always given the next base for type A obstruction. The batter-runner is sent back to first because the ball is dead immediately at the time of obstruction, and since the batter-runner was between 1st and 2nd at that time, the B-R is sent back to first.
Type A Obstruction by Third Baseman during a rundown. Immediate dead ball, obstructed runner given next base. The obstructed runner is always given the next base for type A obstruction, even if they had retreated to the previous base when the obstruction occurred.
In Little League, blocking the plate (or a base) without the ball is Type A Obstruction. The rule is slightly different in OBR, but the effect is the same, immediate dead ball and the run scores. In the first play on this video, the catcher sets up with his foot blocking the runner's path to the plate. This video shows a second similar play that is not obstruction. In the second play, the catcher sets up in front of the plate and then moves to block the plate after he has the ball. That is not obstruction because he is allowed to move into the path of the runner once he has the ball. The catcher can also move into the path of the runner to field the throw.
Ignore what the announcer says about where the throw is, the only determining factors in Obstruction/No-obstruction on this type of play is where the catcher sets up to receive the throw and whether the play was close enough that it affected the play.
Type A Obstruction on Catcher. Immediate dead-ball, batter awarded first base.
As soon as the ball clanks off the catcher and is out of his reach, the catcher is no longer in the act of fielding the ball (it also makes it a fair ball). The catcher is in the way of the batter-runner and obstructs his path to first base when the batter finally decides to run. This is a special case that is in the rulebook--a batter-runner obstructed on his way to first is always given first base.
Type B Obstruction occurs when a play is not being made on the runner at the time the runner is obstructed.
Type B Obstruction by Third Baseman. Delayed dead-ball, runner allowed to score. 3B is not considered in act of fielding ball once the ball goes past him. If you watch the 3B umpire, he holds out his left arm with a closed fist; this is the mechanic for delayed dead ball and tells the other umpires that the runner will be protected on a close play trying to advance.
Type B Obstruction by SS. Delayed dead-ball, runner allowed to score.
Type B Obstruction on First Baseman. Delayed dead-ball, runner given second base. This one happens in Little League all the time and is not an automatic award of 2nd. The runner is only given 2nd if the umpire's judgement is that the runner would have made it to 2nd if the 1B had not got in his way.
Type B Obstruction on SS. Delayed dead-ball, batter ruled out.
Once the ball goes past the SS, he is not in the act of fielding and is guilty of obstruction when he is in the way of the runner, and the umpire calls the obstruction. The play continues and the runner gets thrown out by 30 feet. Umpires determine that the obstruction did not affect the play and the runner is out. Type B obstuction is NOT an automatic award of the next base.
A fake tag that gets a runner to slow down or slide is Type B Obstruction. Type B Obstruction is not always a base award; in this video the umpires judgement was that the runner would not have scored without the slide because the LF got to the ball quickly. If LF had not been there, umpire could have awarded runner home even though he was injured.
A fake tag is also a bush league play and draws a predictable reaction in the next half inning.
But this kind of deke is not obstruction and is just baseball...and it cost the Braves the 1991 World Series.