In hypermedia presentations, one of the main tasks provided by the orchestrator is the synchronization of all presentation objects, which may be achieved by elastic time adjustment of period of exhibition of the objects, or simply timescale adaptation. This technique can be applied at compilation time, in order to keep track of synchronism relationships specified by authors, or at presentation time, to prevent any temporal mismatch caused by transmission or execution environments. This work presents a set of mechanisms to carry out timescale adaptation in MPEG-2 Systems and Video streams, proposing algorithms to perform compression and expansion of exhibition period, also called playback dilation, rate control, inter-media synchronization and clock reconstruction. In order to be performed at execution time, timescale operations are realized directly in compressed MPEG-2 streams, requiring no transcodification.