I know the Orthodox Church views sacrements in the Roman Catholic Church as valid
woa this is news to me
the strongest statement of affirmation i have ever heard of, which is accepted widely among Orthodox (altho this is contestable as well), is that the Orthodox Church DOES NOT/CANNOT know for sure if Latin sacraments are valid or not, and so they (the Orthodox Church) call upon the power of economy in many cases to avoid directly transgressing against the Holy Spirit by redoing, let's say, a baptism that might have been valid the first time (at least this reason is the only one that is serious enough IMO to even consider accepting non-Orthodox sacraments as partially valid).
this discussion, which i do not mean to open up again since i think many threads have covered it already, less often directly addresses the holy mysteries of matrimony and ordination, and so when spartacus said:
even accpeting Roman Catholic Holy Orders for priests
i can affirm that i may have heard of something like this happening, but from friends who do more research than i, so i can supply no references.
as for matrimony, the logic would follow that a non-Orthodox wedding may have partial validity in the act itself, but not complete validity, and maybe that blessing ceremony discussed earlier is the moment in which the Church recognizes it as valid...? i don't know this to be true, im only saying what makes sense. it could be that the holy mystery of matrimony is more than a ceremony, but an ongoing sacrament that remains sacramental in nature throughout the couple's whole life, the idea being that it is a mystery that occurs ONCE only for each couple, but the ONCE extends over their entire life, and so when they become orthodox themselves, so does their marriage.
just my thoughts on the matter