[1] That is why an Australian video tape will play in colour on a Russian TV set.
[2] Eventually it became the standard practice for all SECAM TV sets made to also accept PAL.
[3] In order to be able to watch American video tapes, the people of Europe and Southeast Asia started to buy video recorders that would play back an NTSC video tape and convert the colour component of the video content to PAL, whilst leaving the number of lines the same, and the field rate, slightly slowed down in order to accommodate the exact 64 microsecond line length required for PAL.
Newer TV sets would automatically accommodate the 60 Hertz vertical scan rate, and older TV sets needed a manual adjustment of the vertical hold.
DVD players give the option of converting the whole signal to PAL standards complete with 50 Hertz scan rate.