Re: DVD and VHS formats

tape formats: tapes aren't really created to "prevent you from watching," there are just different formats. pal is europe and secam is another global standard. the US uses NTSC, a different format as well. to view across formats you can do one of the following:
1) buy a PAL VCR. expensive, but if you need this on regular basis, maybe a good idea
2) get the tapes converted to NTSC. many places will do this for you, and not too expensively. here's a yahoo search: Yahoo! Search
3) buy a combo VCR, one which plays PAL and NTSC

DVDs:
DVD's are formatted different by "region." here's a good faq on that: FAQ
It explains the who region locking system. Enjoy.