if you are talking about your internal memory i would highly advise against that, it might be safe but im fairly certain it isnt, now you could turn the external sd into a flashable drive and use the vibrant just to store it but you are better off just buying a cheap 15 dollar thumbdrive from your local electronics store. IMO much safer and less chance of hurting your vibrant.
LG Nexus 5 - black - 32GB - SlimKat | Franco Kernel
Asus Nexus 7 (2013) - SlimKat | Franco Kernel
Samsung Galaxy Nexus - GSM (i9250) - Slim Bean(latest) | Franco Kernel (latest nightly)(retired)
Samsung T-Mobile Vibrant - ICZen (4.0.4) || ASUS Transformer Prime - Androwook || Kindle Fire - Completely stock(retired)