Hi Angel Tsvetkov,
That video is from an earlier build of the engine and the template levels have changed a little bit since then. Some of the materials applied to the floor and other geometry used a lower roughness value.
Right now the Roughness value in the are higher (0.7). You can open the CubeMaterial that is applied to the ground in the template level and adjust the roughness value to be lower, like 0.2 - 0.25 and that should give you a better look for reflections. Also make sure to select the reflection capture and hit Update Capture.
I hope this helps.