To switch from photo mode to video mode, select 
.
For best results, close any open applications before recording.
Record to your phone mass memory, if possible.
If recording videos to a memory card, for best performance, use a compatible, fast, high-quality microSD card. The recommended microSD card class is 4 (32 Mbit/s (4 MB/s)) or higher.
Before first use, back up any important content on the card, and use the phone to format the card, even if the card has previously been formatted or used in a Nokia phone. Formatting deletes all content on the card.
If the memory card gets slower over time, back up any important content on the card, and use the phone to format the card.