The president did not mention the video on Monday in the blizzard of Tweets he sent out wishing his former press secretary good luck on “Dancing with the Stars,” defending his recent decisions on Syria and attacking Democrats for their impeachment inquiry. But Stephanie Grisham, the White House press secretary, said Mr. Trump condemned the video. It was shown at a meeting of American Priority, a pro-Trump group, celebrating free speech at Trump National Doral Miami, which he owns.

Many of the Trump supporters who attended — including Gov. Ron DeSantis of Florida, the former White House press secretary Sarah Huckabee Sanders and Donald Trump Jr., the president’s son — said they did not condone the violence portrayed in the video and were not aware that it had played on a loop in a conference room next to the Donald J. Trump Ballroom at the resort.

The goal of the online community that makes and shares grisly videos like this is to use what are known as “spicy memes” to fire up the president’s base online, stir outrage among his opponents and provoke coverage by the mainstream media, which often helps amplify the messages.

Some of these meme-makers make money from their creations by soliciting donations or running ads on YouTube. (Data from SocialBlade, a website that tracks social media statistics, estimates that TheGeekzTeam has earned less than $2,000 from his or her channel over the past year.) Others do it purely for the notoriety — or, best of all, an approving retweet from the president.

TheGeekzTeam has been a prolific meme-maker for several years, posting videos with titles like “Captain MAGA” and “Trump: The Punisher” to YouTube and to r/the_donald, a large pro-Trump forum on Reddit. The video shown at the American Priority meeting was first posted on YouTube in July 2018.