Complex sentence: Columbia House began distributing NTSC tapes, via mail order in 1997, followed by repackaged collector editions and 3 tape box sets in 1999, by which time the original telefilm had been replaced by the re-edited TNT special edition.
Split into simpler sentences: Columbia House began distributing NTSC tapes, via mail order in 1997. Repackaged collector editions and 3 tape box sets followed in 1999, by which time the original telefilm had been replaced by the re-edited TNT special edition.