Five-year-old Jaden Wilson was diagnosed with Grade 4 brain stem tumour last September, which gave him about a year to live. So this year, his father decided to make the boy's birthday as special as possible.
Mr Mike Wilson dressed up as the boy's favourite action hero Spider-Man, made a surprise appearance in front of their home, and gave the boy a big hug.
The father filmed the special moment on a Go Pro camera and uploaded a clip on YouTube on Nov 16.
Mr Wilson wrote in his video description: "I had a replica Spider-Man suit made, so I could surprise my son on his 5th Birthday... I'm so proud i managed to do this for him."
He added: "Today he is still with us, fighting it all the way, but at least he has Spider-Man to take care of him."
Mr Wilson, who lives in the UK, describes himself as a professional freerunner, parkour choreographer and urban movement specialist. He has also set up a support page for his son on Facebook.
Those who commented on the video had nothing but good things to say about it, with some even admitting to shedding a tear or two.
One viewer, Adam Sheritt, wrote: "I'm sorry to hear about his prognosis, but it seems that you are making the most of the time you have left together. So glad you captured this on film for the world to see."