I'm running DSM 5.0 & the same version of video station as you & have an iphone running IOS 8.1 with dsvideo version 2.4-200 streaming to 2 Samsung smart TV's without problems.
you could try a Linux livecd or a windows boot disk/usb, anything really that will boot & allow you to delete the existing partition, you don't need to format. Once done DSM will see the disks as new.
How are you trying to connect to the NAS, via the web assistant or the Synology Assistant PC client. If using the web assistant try using the PC version as I sometimes find that works better.
Although your HDD's state 3gb, their actual formatted capacity is 2.73gb, so if you put them in a SHR array the maximum space you will get after DSM is installed is around 5.44gb.