That is marketing - There is no such thing as "-R is meant for video", we are talking about two writing methods but at the end delivering the same results.....it is still a DATA disc..... a DVD containing a VIDEO_TS with the required files according to the DVD standard. The -R is better in terms of compatibility, not because you will get better looking videos Yes -R might be compatible with more players, however using +R booktyped to DVD-ROM will provide even better compatibility - and the +R format is more tolerant.
The fact some players will not play a +R booktyped to DVD-ROM will depend on many factors, including the type of media used.
I have had no problem playing back Taiyo Yuden +R (bitset to DVD-ROM) on even the fussiest players that did not recognise neither -R nor +R, including very first generation DVD players.... I was not able to get the same results with say a RITEK +R or other brands. So media is a factor too.
Personally I have always used +R for making video and never encountered ANY problem.