Greg's guess is probably the closest you will get to an accurate answer.
IPv6 traffic is blocked by default.
Lest's break it down a little more:
Remote Host: FE80:0:0:0:943A:C7BF:A417:1F96
This is the equivalent to an APIPA address. An address that is automatically assigned to a machine, by itself from a failure to acquire an address from a DHCP server and not having one statically assigned. The IPv4 equivalent would be 169.254.x.x Thus allowing for all clients on a local subnet to be able to continue to communicate with each other if failure of a DHCP server were to occur.
Local Host: FF02:0:0:0:0:0:0:C is the default broadcast address for SSDP (Simple Service Discovery Protocol). It's IPv4 equivalent is: 239.255.255.250
SSDP uses UDP traffic, so this is normal logs and it is also normal to see it blocked.
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Do you have Windows 7/Vista or Linux/Mac boxes that have IPv6 capabilities?
Basically, one or more (depending on the log files and different Remote Host IPs) is just sending a regular packet every now and again (UDP). It is asking for anyone using IPv6 traffic on the segment, to reply and say: "Hey, I'm here and these are the services I am running and the ports they are using". Like, DHCP, Wins, DNS, NTP, IIS, Apache, etc.
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Now, back to the original question. Safe and to allow?
Well, from the machine blocking the requests, open a command prompt (elevated) and:
PING -a FE80:0:0:0:943A:C7BF:A417:1F96
The machine should return it's registerd name.
If you know and trust it, you could safely disregard these messages. IPv6 is not completely pass through (yet), so you should consider the possibility of disabling this rule might allow external traffic (that you don't want) into your network.
Hope that helps.
Cheers!