Working on swingarm/linkage bearings, quick question

[ams14]

Sorry, this might be a dumb question: I'm working on my swingarm/linkage bearings this weekend on my 06 yz450f. Some are in good shape, am replacing a few (got All Bals kit).

Question: When I put the outer rubber grease seals in, what is the orientation? There is basically a channel on one side and the other is flat (and has the part number). They are currently installed in both orientations depending where on the bike (maybe from previous owner). I was thinking it was 'channel in', but if I look at this video, right around minute 6, it looks like he is putting them in 'channel out'.

[stroker101]

i always install grease seals with the part # facing out,...channel to the insde, sealing edge out

[peo]

Think about what the seals are about to protect, and you will find the right way for mounting (which is not always with the part # facing out):

"channel" / lip should be facing towards what it is sealing, in case of a fork inner tube, it should protect against the oil leaking out, and in case of the linkage it should protect from water coming inside, that is, the channel/lip should be mounted facing outwards (as you see in the assembly video, as well as the Clymer and Yamaha original manuals mention)