1) You are too upright. Bend over more. Point your nipples to the floor. Push your ass back.
2) You're in thoracic flexion. Chest needs to be up. Think chest up but ribs down. Brace hard and lock those ribs and abs tight while maintaining the chest up position. Think Superman Chest. Read this: Identifying and Correcting Thoracic Spinal Flexion in the Squat | Bill Hannon
3) Knees should be pushed out over your toes. If your knees aren't going out you might be smashing your Anterior Superior Iliac Spine (ASIS) to your femur (thighs) which might be causing an impingement of the hip flexors. Can't really tell from this angle. Read the sticky about filming the lifts! Read this: https://startingstrength.com/article...2_rippetoe.pdf
4) Knees going forward can be corrected with "staying tight in the bottom". People tend to relax their quads at the bottom of the squat because everything is stretched and hard to maintain. If you relax your quads you tend to get "knee slide" as seen in your video. SO GET TIGHT AND STAY TIGHT. Do not relax @ the bottom. A TUBOW might be very useful in this situation. (YouTube)
Another problem is that your feet are moving around during the lift. Your feet need to planted, "glued to the floor". there should be no rocking back or forth. Going on your toes @ the bottom might be causing your knee slide. Practice staying over your mid foot by using this method: During your warm ups imagine the bar moving straight up and down a slot in the air, right over the mid foot. Do the reps while counting 1-2-3 on the way down and then without stopping @ the bottom count 3-2-1 as you go up. This is called a Tempo 3-0-3 SQ. Do this slowly and really concentrate on keeping the knees and quadz tight, just touching the TUBOW, and keeping the bar over mid foot. Do a couple of warm-up sets using this protocol and continue to your work sets keeping in mind the practice you just had.