During the last decade, CPM developed new diagnosis techniques to evaluate more precisely coke oven battery ageing. Among them, the Videofil machine was specially devoted to the inspection of the hot refractory brickwork of coke oven chambers and heating flues. Since the first machine was put into operation, significant improvements have been performed and the last generation of Videofil machine is fully automated, more efficient, more reliable and easier to use. This machine is extensively used in coke plants, but also in the whole steel industry. It contributes to extend the plant service life, to decrease the maintenance costs and to increase the plant availability.