Sure, how much context do you want?
10 minutes before, he's talking about donors corrupting politicians
5 minutes before, he's talking about job creation under Obama, then talks about taxes and business regulations, him vs. Clinton
3 minutes before, cont.
1.30 minutes before, cont.
50 seconds before, policy distinctions between him and Clinton
15 seconds before (ish) he talks about Hillary on the second amendment
Makes the comment
15 seconds after, he says he and Hillary are tied in the race for the white house
20 seconds after, he says Scalia should have never died, was expected to serve for 10 more years
50 seconds after, he talks about his endorsement from the NRA
1.10 minutes after, he talks about his supreme court picks
1.30 minutes after, relatively vague standard republican talking points on guns (criminals don't follow the law, etc.)
1.50 minutes after, talks about Hillary wanting open borders and the harm of drugs
2 minutes after, talks about his wall
3 minutes after, talks about Iraq
It's easy to say, "well there's more context than those 30 seconds," but it's way harder to find any relevant comments elaborating on what he had said. Pretty simply, because those comments don't exist. I've watched most of the rally, he never elaborates on how these second amendment people can stop Hillary's appointment of justices were she to be elected.
Perhaps if right after the comment, he had said, "so we need to do our best to keep her from being able to make those picks in the first place. to do that, i need all you second amendment loving folks to get out there, make phone calls, go out and knock on doors, make sure when everybody goes out to the polls in November they vote, "Trump! *crowd screams* *woooo* *yayyy* *make america great again yaaa* " then that'd obviously be an acceptable comment. but that never happened. Instead, the context of surrounding comments leads us to believe that he just popped around the notion that some gun lovin murican patriot go out and assassinate Hillary Clinton.
if you seriously consider condemnation of comments inciting violence as detracting from the legitimacy of a groups stances, then my heart truly goes out to you. God bless