I haven't been able to verify either way. It' definitely wasn't from the parade.
However, FOX News definitely added fake crowd noise to Trump's speech
https://www.msn.com/en-us/news/politics/fox-news-accused-of-adding-fake-applause-during-trump-parade-live-stream-they-had-to-help-him-out/ar-AA1GPDVP
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Users pointed out that footage of Trump's remarks during the event which aired on FOX News was accompanied by applause sounds that didn't sound correct for the setting. Furthermore, they pointed out that the footage of the same point in the event aired on other networks, such as PBS, was not accompanied by the same cheering.
"Sound engineers pointing out in the comments that the applause is from an indoor audience on an outdoor event," wrote one user who reposted the video on Bluesky.
"I guess they had to help him out. The entire day was a fiasco. Too embarrassing," commented one user.
"No need to be a sound engineer (although I dabble) It's Trump, the place was empty, in an outside venue. Where is the reverb coming from?" said another.