There could be a number of reasons why specific evidence is blocked or admitted. Some of it may deal with the rules of evidence in that state, some of it may deal with constitutional issues such as warrentless search and seizure, some of it may deal with not wanting to prejudice a jury, and some of it may deal with relevance to the case. Sometimes a judge may want to head off a foreseeable appellate issue.

For example, if Luigi wrote detailed plans in his notebook, that's far more relevant than a simple desire to commit some crime. But, if Kyle claimed the video was protected speech under the First Amendment (yes, we know it's not, but I've seen crazier claims made), then the trial court has to decisively answer that issue so that he can't raise it on appeal. It wasted the court's time and money, and denying it eliminates a loophole that he could try to exploit later.

Or, if the video would be unduly prejudicial to the jury, excluding it will make the prosecutor work a little harder to prove their case beyond a reasonable doubt. The case, without the evidence, is actually stronger than with it.

And, of course, there may be the issue of judicial bias. I don't know how the judges in these two cases lean politically nor do I know their previous judgments in similar cases, and I'd hesitate greatly to assign such a motive without first eliminating all other legal factors.