I don't really understand this

.
I'm a Lovefilm customer, and use it for physical discs. I'm on the unlimited discs per month product. I think it included some online streaming, but I never really used it.
The email I got from Lovefilm said
The lovefilm website now redirects to Amazon, with two obvious things to click:
- Manage LOVEFiLM By Post Membership says: "On 18 March 2014 your card will be charged £4.00"
- Manage Your Prime Membership says: "On 18 Mar 2014, you'll be charged £5.99 for month of Prime Instant Video."
So that I guess means that my £9.99 per month hasn't changed, but it's now being split up into the discs by post cost separate from the online streaming cost (which I never use!).
So could I cancel the £5.99 Prime Instant Video part of it, and keep the £4.00 LOVEFiLM By Post part?
And if I decide to step up to full Amazon Prime (for free postage etc), that £79/yr would replace the £5.99/pm Prime Instant Video cost? Multiplying out the £5.99 Prime Instant Video by 12 months is £71.88 anyways

... so only £7 less?