1st source: webcam, where the guy sits with his chair in front of a green screen. With the chroma key filter the background is removed.
2nd source: An image with yellowish-orange fire-like background with a white border that occupies 2/3 of the desired portrait. This source is put under the 1st source, so the guy is towering it. The webcam source is delicately placed in a way that it doesn't cover the bottom white border of the image source but extend the top.
In case the 2nd source is animated, it's not an image but a movie file with a prepared fire-like animation playing in loop.