Method for synchronising video and data, which comprises: i) providing at least one marked video signal that includes one video signal which comprises at least one marked frame (Fm) that includes one watermark on one region of at least one original frame, wherein said watermark includes encoded synchronisation information for synchronizing said at least one original frame with data associated thereto; ii) sending said marked video signal from an emitter to a receiver with access to a data signal that contains said associated data; and iii) performing a synchronisation step which comprises said receiver extracting the synchronisation information included in the watermark of said marked frame (Fm) of the marked video signal, decoding it and using it to synchronise said original frame with said data associated thereto; the method being characterised in that: said step i) comprises: ia) generating said marked video signal by extracting an image fragment from a region of said original frame, and arranging said watermark on said region of said frame, replacing said extracted image fragment, to obtain said marked frame (Fm); and ib) generating said data signal, including therein said extracted image fragment; said step ii) comprises sending both said marked video signal and said data signal to said receiver, through communication paths which are independent from one another; said step iii) comprises: iiia) performing said synchronisation step; and iiib) said receiver performing an additional synchronisation step which comprises: iiib1) obtaining, from the data signal, the image fragment included therein, iiib2) obtaining, from the marked video signal received, an incomplete frame (Fr) that includes said original frame without the watermark and without the extracted image fragment, and iiib3) attempting to reconstruct the original frame from the information obtained in iiib1) and iiib2), and, if the reconstruction is successful, determining that the frame of the video signal and the associated data of the data signal are duly synchronised. i) providing at least one marked video signal that includes one video signal which comprises at least one marked frame (Fm) that includes one watermark on one region of at least one original frame, wherein said watermark includes encoded synchronisation information for synchronizing said at least one original frame with data associated thereto; ii) sending said marked video signal from an emitter to a receiver with access to a data signal that contains said associated data; and iii) performing a synchronisation step which comprises said receiver extracting the synchronisation information included in the watermark of said marked frame (Fm) of the marked video signal, decoding it and using it to synchronise said original frame with said data associated thereto; said step i) comprises: ia) generating said marked video signal by extracting an image fragment from a region of said original frame, and arranging said watermark on said region of said frame, replacing said extracted image fragment, to obtain said marked frame (Fm); and ib) generating said data signal, including therein said extracted image fragment; ia) generating said marked video signal by extracting an image fragment from a region of said original frame, and arranging said watermark on said region of said frame, replacing said extracted image fragment, to obtain said marked frame (Fm); and ib) generating said data signal, including therein said extracted image fragment; said step ii) comprises sending both said marked video signal and said data signal to said receiver, through communication paths which are independent from one another; said step iii) comprises: iiia) performing said synchronisation step; and iiib) said receiver performing an additional synchronisation step which comprises: iiib1) obtaining, from the data signal, the image fragment included therein, iiib2) obtaining, from the marked video signal received, an incomplete frame (Fr) that includes said original frame without the watermark and without the extracted image fragment, and iiib3) attempting to reconstruct the original frame from the information obtained in iiib1) and iiib2), and, if the reconstruction is successful, determining that the frame of the video signal and the associated data of the data signal are duly synchronised. iiia) performing said synchronisation step; and iiib) said receiver performing an additional synchronisation step which comprises: iiib1) obtaining, from the data signal, the image fragment included therein, iiib2) obtaining, from the marked video signal received, an incomplete frame (Fr) that includes said original frame without the watermark and without the extracted image fragment, and iiib3) attempting to reconstruct the original frame from the information obtained in iiib1) and iiib2), and, if the reconstruction is successful, determining that the frame of the video signal and the associated data of the data signal are duly synchronised. iiib1) obtaining, from the data signal, the image fragment included therein, iiib2) obtaining, from the marked video signal received, an incomplete frame (Fr) that includes said original frame without the watermark and without the extracted image fragment, and iiib3) attempting to reconstruct the original frame from the information obtained in iiib1) and iiib2), and, if the reconstruction is successful, determining that the frame of the video signal and the associated data of the data signal are duly synchronised.