"I was down there also, but I'm not considering myself a first responder. But I was down there. I spent a lot of time down there with you."
Likely false. (As elaborated in the linked video, watch it in whole for a strong rebuttal of the claim, and others.)
On 9/11, Donald Trump was sitting in his office in Trump Tower, and actually phoned in an interview.
"Everyone who helped clear the rubble ― and I was there, and I watched, and I helped a little bit..."
If you look at the quotes closely, he does not actually claim much, though he makes it sound like much more. He admits to having been there for "a lot of time", that he "watched", and that he "helped a little bit". You could arguably say this for anyone who stood there, gawked a lot, and perhaps passed a water bottle or moved one shovel of dirt while posing for the cameras.
Only that not even a picture exists.
There is a total absence of evidence that Mr. Trump did any amount of helping worth mentioning, and statements from people like Richard Alles (at the time Battalion Chief of the FDNY), who was supervising search and rescue teams for two weeks after the attacks and said that he "spent many months there myself, and I never witnessed him".
User CL. posted a video link of an interview given by Mr. Trump. About this video, The Daily Mail had this to say (emphasis mine):
In that interview, he said he had 'hundreds of men inside working' and offered a colorful description, speaking about how five men had been found alive that day.
The claim was widely circulated on September 13, and was featured on a chyron under Trump as six men being rescued, but in fact was untrue. The last survivor was pulled from the rubble 27 hours after the planes hit.
So Mr. Trump was not, indeed, close enough to the actual rescue efforts to know the rumor for a rumor. The Daily Mail continues:
Trump therefore certainly came close to Ground Zero, although his interviews showed that if he did actually go to the site itself, he must have cleaned up before appearing on television; conditions there meant anyone who went near it was covered in dusty and debris.
The claim about "hundreds of men" is in turn challenged. Quoting the New York Times article,
Mr. O’Brien, the author, said the size of the Trump Organization at the time was “a little bit over a dozen people,” which would have made it impossible to send hundreds of people to participate in the relief effort. At the time, Mr. Trump had a large number of casino workers based in Atlantic City, but there is no documented evidence of him marshaling his resources to aid in the relief effort.
Snopes quotes Richard Alles (see above):
“This is the first I’m hearing of it,” Alles told us by phone. “There would have been no need for that. Between police, fire and the construction crews, we had it all covered.”
John Feal, who was at Ground Zero as a construction demolition expert, is quoted that he...
...didn’t see evidence of hundreds of workers hired by Trump at the site, and added that by 15 September 2001 the area was on lock down. “There was no way anyone could get in and out of there without a [government-issued] badge,” he told us.
As for helping via donating money, Mr. Trump claimed that he donated $10,000 USD to the 9/11 fund, a claim which the office of New York City's Comptroller Scott Singer refuted.
Bottom line, we have zero evidence of Mr. Trump having "helped" other than his own words.