You can check for yourself by clicking on the video below. The Royal Observatory says it will be hard to determine what it really was, as the footage it received is not of the best quality, and is filmed from the same angle.
Jan Cuypers told the VRT that "it is not impossible that it's a meteor or the remains of a satellite, but it's very improbable. We only received reports from people from the same area, whereas a meteor should be visible in a larger area. The object can clearly be seen below the clouds. Chances are small that it's something from space."
It was suggested it could have been a small rocket or a drone, but in the afternoon Jan Cuypers told the VRT that was probably an ordinary plane. "Looking at it from a certain angle, the sun made the exhaust line look like a plume of smoke. You can never be 100% sure, but this explanation seems realistic to me."