example from @marcvanolmen and @chris for loading assets with PHImageManager

loadVideo.swift

let imageManager = PHImageManager.defaultManager()
    let videoRequestOptions = PHVideoRequestOptions()

    videoRequestOptions.deliveryMode = .HighQualityFormat
    videoRequestOptions.version = .Current
    videoRequestOptions.networkAccessAllowed = true
    videoRequestOptions.progressHandler = { (progress: Double, error: NSError!, stop: UnsafeMutablePointer<ObjCBool>, [NSObject : AnyObject]!) -> Void in

        NSLog("Progress: %@", progress.description)
    }

    videoRequestOptions.progressHandler = { (progress: Double, error: NSError!, stop: UnsafeMutablePointer<ObjCBool>, [NSObject : AnyObject]!) -> Void in

        NSLog("Progress: %@", progress.description)
    }

    imageManager.requestAVAssetForVideo(nextAsset, options: videoRequestOptions, resultHandler: { (avAsset: AVAsset!, avAudioMix: AVAudioMix!, info: [NSObject : AnyObject]!) -> Void in

        if let nextURLAsset = avAsset as? AVURLAsset {

            let sourceURL = nextURLAsset.URL

            if NSFileManager.defaultManager().fileExistsAtPath(sourceURL.path!) {
                NSLog("exist file")
            }

            var data = NSData(contentsOfURL: sourceURL)

            if let aData = data {
                NSLog("length : <\(aData.length)")
            }
            else {
                NSLog("no data read.")
            }
        }
    }