It's the VHS version. Every video copy I've ever seen has fine print underneath the title that reads "Special Longer Version".
You haven't looked hard enough then.
The original theatrical version was available as a VHS/Beta. In 1983, after ABC-TV premiered its extended version, that was released on VHS/Beta as the "Special Longer Version".
When the movies came out in a widescreen boxed VHS set, many people assumed (by the running time on TMP's box art) that it was again the SLV of TMP being re-released but that timing was a misprint. The only widescreen version of TMP on VHS is the theatrical version.
Then along came DVD-Diector's Edition, retaining some of the SLV footage (including the Rhaandarite ensign scene I mentioned), but segments that weren't chosen by Robert Wise for his DE, were shunted off into the bonus features section.